UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE BLACK WIDOW SPIDER W. B. HERMS, S. F. BAILEY, AND BARBARA McIVOR Mature female black widow spider in web with egg sac. (About two and one-half times natural size.) BULLETIN 591 June, 1935 UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA CONTENTS PAGE Introduction 3 Distribution 4 Natural habitat 4 Description of the mature spider 4 Preying habits of the mature spider : 6 Mating habits 7 Proportion of sexes 8 Life history 9 Description of the immature stages 12 First instar 12 Second instar 12 Third instar 12 Fourth instar 13 Fifth instar 13 Sixth and seventh instars 13 Eighth instar 13 Longevity 14 Venom apparatus 15 Nature of the venom 16 Laboratory experiments 17 Effect of the bite on man 21 Clinical case records 22 Treatment 24 Control 25 Literature cited 29 THE BLACK WIDOW SPIDER 1 W. B. HERMS, 2 S. F. BAILEY/ and BARBARA McIVOR 4 INTRODUCTION The spider Latrodectus mactans (Fabr.) now commonly known as the "black widow" was first described from America by Fabricius in 1775, under the name Aranea mactans (Fabricius, 1775). 5 It belongs to the arachnid family Theridiidae. Like many other species the specific name of this spider has suffered many synonyms (Petrunkevitch, 1911), among them the following : Lathrodectus malmignathus var. tropica van Haaselt, Latrodectus perfidies Walck., L. insularis Dahl., L. datatus C. Koch, L. apicalis Butler. Many common names are also applied to this spider, among them in addition to "black widow" are "hourglass spider," "shoe-button spider," "Pokomoo" (Merriam, 1910), a name used by the California Indians who probably referred to this species as "a small black spider with a red spot under his belly," "cul rouge" (red rump) of Santo Domingo, "mico" of Bolivia, "lucacha" of Peru (Escomel, 1917), "Arana capulina" of Mexico (Baerg, 1929a) , and other colloquial names. While spiders in general have been considered poisonous, though largely erroneously, for centuries, the group to which the black widow belongs in particular has been classed as poisonous for only about a century. Many of the early reports of spider bite traceable to the black widow came from the southern states and from 1889 to 1894 were fre- quently mentioned in Insect Life (Riley and Howard, 1889-1894) . After the rapid increase in the population of California during the latter part of the Nineteenth Century, reports of poisonous spider bites began to be received from this State. Wade (1889) cited a case in 1889, Brown (1895) reported 22 cases in 1895, and Browning (1901) listed 70 cases in California in 1901. Bogen (1926) states that more than 150 such re- ports had been placed on record by 33 physicians in the United States during the last century. Six years later he (Bogen, 1932) listed a total of 380 cases from 18 states, of which 250 were from California. Numer- ous popular magazine and newspaper articles have appeared from time to time reporting local cases and warning the public of this arachnid. i Received for publication January 30, 1935. 2 Professor of Parasitology and Entomologist in the Experiment Station. 3 Instructor in Entomology and Junior Entomologist in the Experiment Station. 4 Graduate student in the Division of Entomology and Parasitology. 5 See "Literature Cited" for complete data on citations, which are referred to in the text by author and date of publication. [3] University of California — Experiment Station DISTRIBUTION This species, Latrodectus mactans, like most of the members of the genus, favors warmer climates. It has been reported in nearly every state of the United States, as well as in Canada. Petrunkevitch (1911) and Baerg (1929a) have given the distribution of the black widow spi- der as ranging from New Hampshire in North America to Tierra del Fuego in South America, including Mexico, Central America, and the West Indies. The increase in reported cases of poisonous spider bites has probably been the result of more accurate diagnosis as well as the spider's gradual change of adaptation from its natural habitat to that of man's protective shelters. NATURAL HABITAT In its natural habitat the black widow spider is found with its web and egg sacs in protected darkened locations, such as vacated rodent burrows, under stones, logs, and long grass, in hollow stumps, and brush piles. It takes up its abode in man-made structures ranging from the out- door privy to and including cellars, garages, hen houses, barns, pump houses, and the home. The females and immature individuals are found most commonly in corners or in such locations as afford both protection and support for the web. As a rule the females are not aggressive unless agitated or exceed- ingly hungry. When guarding the egg sac the female, if disturbed, is particularly prone to bite. The spider is present throughout the year but relatively more abun- dant in the late summer and early fall. Many females have reached ma- turity by that time, while a few are carried over from the brood of the previous year. The mature males, as pointed out later, live but a few weeks. These observations coincide with the incidence of poisonous bites by months as reported by Bogen (1926) who states that the majority of the spider-bite cases are recorded during July to October, inclusive. DESCRIPTION OF THE MATURE SPIDER The adult female is glossy black to sepia and densely clothed with short almost microscopic hairs which give it a naked appearance. An irregular white stripe, a remnant of nymphal pattern, is sometimes pres- ent on the dorsal anterior margin of the abdomen. The characteristic crimson hourglass marking on the underside of abdomen (frontispiece), rarely altogether absent, varies among individuals from the distinct Bul. 591] Black Widow Spider Fig. 1. — Adult black widow spider: A, dorsal view of mature female; B, dorsal view of male; C, ventral view of male. (About three times natural size.) 6 University op California — Experiment Station hourglass design to a design comprising two or more distinct triangles or occasionally only an irregular longitudinal area. An occasional speci- men has a crimson spot at the posterior end of abdomen on the dor- sal side, just above the spinnerets. The abdomen is globose and often likened to a shoe button (fig. 1). The average width of the abdomen is 6 millimeters, or Vi inch, and length over all (legs extended) about 40 millimeters, that is, about 1% inches. The abdomens of the gravid fe- males often measure 9 by 13 millimeters (% by y 2 inch) . The color pattern of the adult male (fig. 1), while exhibiting consid- erable variation, approaches that of the immature female spider. Occa- sional mature males are almost black but retain some of the abdominal markings of the immature form. The terminal segment of each palpus (mouth feeler) appears like a large, black knob at the front of the head and contains the ejaculatory sexual apparatus, a portion of which re- sembles a coiled watch spring. The abdomen measures about 3 milli- meters, or % inch, in diameter and the length over all is about 30 milli- meters, that is, about 1% inches. PREYING HABITS OF THE MATURE SPIDER The habits of the adult black widow spider like most spiders offer an extremely fascinating study. Once a web is established (fig. 2) in a suit- able location, the female spends the rest of her life feeding on the prey ensnared in this web and guarding such egg sacs as she may deposit. "Whether the prey be a nocturnal moth, cricket, or domestic fly, the technique of capturing, killing, and finally sucking the fluids from the victim is very consistent. Barrett 6 believes that the spider puts its eyes to a minimum of use and depends largely upon vibrations of the web as an indication of a trespasser, or prospective meal. The coarse, permanent web is not particularly viscid in nature, but inadvertent insect visitors become temporarily entangled and in struggling to free themselves in- form the owner of their presence. The spider always approaches the vic- tim backwards, extending a freshly spun strand of viscid silk with either one or both hind legs, and attempts to tie down the thrashing append- ages. If the captured prey appears particularly obstreperous, the spider ejects from the spinnerets large viscous droplets which dry quickly after the manner of rubber cement, and if the victim becomes entangled by these jets, escape is impossible. At about this point a lethal bite is usually administered. After being bitten the victim struggles violently, and in the course of a few minutes of progressively weaker tremors, dies. The body fluids are sucked from the trussed up victim at the leisure e Barrett, E. E. A preliminary study of the life history of Latrodectus mactans Fabr. (Unpublished notes.) 1927. Bul. 591] Black Widow Spider of the captor. After the meal is finished all points of attachment between the remains of the prey and the web are cut loose allowing it to drop from the web (Rau, 1924). The diet of the black widow is largely a "come-what-may" menu com- posed of practically any insects of the locality, small spiders, and even centipedes and sowbugs. It is surprising to learn the number of insects Fig. -Typical web of black widow spider. Note molted skin in center. that an individual spider consumes during its lifetime. Accurate records kept of the food of isolated specimens have totaled, in the life of an indi- vidual spider, as high as 250 houseflies, 33 vinegar flies (Drosophila) , 2 crickets, and 1 small specimen of Latrodectus mactans. In considering the economic status of this spider, its large diet of prevailing pests is a matter which should not be put aside lightly. It is interesting to note in connection with the diet that one individual (a male) was reared on a diet of its own species exclusively. MATING HABITS After molting the last time the male leaves its web and seeks a mate. In this active, wandering state the male makes no attempt to capture prey but will occasionally suck up a small amount of water or liquid food 8 University op California — Experiment Station if the opportunity is offered. If fortunate in finding a likely mate, the male vibrates his abdomen rapidly causing the entire web to vibrate; the female may produce reciprocating movements. Cautiously the male approaches and strokes the female with his forelegs. It is a dangerous game the suitor plays, for if the female is not ready for his advances, death may result. On the other hand, if the female accepts his advances, the wooing begins. If agreeable, the female remains quiet and allows herself to be spun up in a delicate web. Once the web is successfully spun the male effects coitus by applying the spring-like apparatus of either palpus to the female genital opening. Occasionally this is re- peated. After coitus the female easily frees herself and in many in- stances ensnares and feeds upon her mate. The infrequent observance and recognition of the male of Latrodectus mactans, together with the mariticidal habit of the female, has given rise to the name of "black widow." However, if other food is immediately available, often the male is not killed and in due course of time dies a natural death. In the lab- oratory the males will readily mate a second time, but the females do not evidence such a tendency. Comstock (1914) states that in some male spiders the seminal fluid is transmitted from the sexual organs (in the abdomen), which lack any ejaculatory apparatus, to the palpi and is there stored for some time previous to mating. A delicate web appears to be spun upon which the fluid is emitted and then collected by the palpi. This process has been observed by us in L. mactans. PROPORTION OF SEXES The exact proportion of males and females is a difficult thing to deter- mine, since it is almost impossible to distinguish between the two until the nymphal spiders are about one-third grown. Considerable mortality results among the young spiderlings, and the individuals originating from one egg sac become widely scattered which makes a true count diffi- cult or even impossible. Of one series consisting of 55 individuals reared in the laboratory, 31 males reached maturity, and of 119 individuals observed out of doors under natural conditions, only 21 were males. When reared individually under laboratory conditions there appears to be an equal sex ratio. Bul. 591] Black Widow Spider LIFE HISTORY The gravid female, when ready to deposit her eggs, forms a loosely woven cup of silk which hangs downward and while clinging inverted to its rim emits the eggs singly with rapid but regular upward flexures of the abdomen. The eggs which appear to be forced into an expanding, gelatine-like film gradually fill and adhere to the silken cup. The open end of the cup is then covered with loose strands of silk and the whole enclosed in a tough, water-tight covering of silk. The entire process con- sumes from 1 to 3 hours. Shortly after the egg sac is completed the film Fig. 3. — Egg sacs of black widow spider (about two times natural size) with eggs (on right) removed from a sac. (Eggs about four times natural size.) surrounding the eggs seems to evaporate and the eggs are free to roll about within their envelope. Egg laying usually takes place during the night. In California these white or buff-colored egg sacs have, been found suspended in webs out of doors from March to October, inclusive. Egg laying takes place when the eggs are fully matured but may take place in the laboratory where food is plentiful throughout the year. The egg sacs (fig. 3) measure from 12 to 15 millimeters (% to % inch) in diam- eter, are usually oval in shape, and may contain from 25 to 917 (Lawson, 1933) spherical eggs, each of which is about 1 millimeter (% 2 inch) in diameter (fig. 3). Females have been observed to spin from one to nine egg sacs a season (Herms, 1923; Rau, 1924; Baerg, 1929&; Lawson, 1933) . Barrett 7 states that two unmated females under observation laid 7 Barrett, E. E. A preliminary study of the life history of LatrodecUis mactans Fabr. (Unpublished notes.) 1927. 10 University of California — Experiment Station eggs that failed to hatch. We have never observed egg deposition on the part of mature virgin females. Fertile, mature females in isolation have produced egg sacs in the fall and, surviving the winter, have laid addi- tional egg sacs the following spring, both groups of eggs being fertile. The time between the deposition of successive groups of eggs varies from about one week to about four months. The incubation period de- pends on the temperature and at nortnal summer temperatures requires about 20 days in the interior of California, the observed extreme range being from 14 to 30 days. The majority of the eggs usually hatch but not simultaneously. In the case of several egg sacs, each being formed by one female, the later lots appear to contain many sterile eggs. The spiderlings after hatching spend some time — varying from 4 days in the summer to about one month in cooler weather — within the egg sac before emerging from one or more small holes which they make in the tightly woven envelope (fig. 3, upper left). The first molt, previous to which the spider cannot feed, occurs from one to two weeks after hatch- ing. Usually the entire first instar (and sometimes the second) is spent within the egg sac, and at emergence the molted skins are left behind together with the egg remnants. There is a tendency on the part of the spiderlings to cluster for a few days after emerging from the egg sac, and cannibalism rules during this time. The spinnerets appear to be capable of functioning at the time of emergence, but the extremely deli- cate web is capable of holding only the smallest of prey, such as gnats, mosquitoes, and other tiny spiders. The mother if confined with her young will not feed upon them even though extremely hungry. Shortly after emerging and after a brief period of clustering, the nymphal spiders disperse by means of nearly invisible strands of silk. For several weeks they move about in the vicinity of their birthplace and suffer a high mortality from predaceous spiders, particularly and as already stated, from their own species. Barrett 8 considers that after the fourth molt the immature spiders become negatively phototropic, that is, go away from light. We have observed that when about one-third grown the female spiders establish themselves in some protected niche, construct small, loosely woven webs of their own lacking in specific de- sign (fig. 2), or, rarely, take possession of an abandoned funnel, sheet, or irregular web. Lawson (1933) states that they form a funnel and often hide in a cell in the ground. Once settled they remain in the chosen lair capturing progressively larger prey and extending the web as they approach maturity. s Barrett, R. E. A preliminary study of the life history of Latrodectus mactans Fabr. (Unpublished notes.) 1927. Bul. 591] Black Widow Spider 11 The number of molts that the black widow experiences varies, and the length of the intervening periods is even more inconstant, seemingly conditioned by the season and the amount of food assimilated. The aver- age number of cast skins shed by the male is five. At optimum tempera- tures and with plenty of food this number is often reduced to three; under less favorable conditions resulting in slower growth, a series of six skins may be shed. The sexes may be distinguished by the palpi, or feelers, which in the male are swollen or knoblike (fig. 1), while the female possesses slender palpi. Subsequent to acquiring this secondary Fig. 4. — Newly molted, immature female (sixth instar) black widow spider, removed from web, with cast skin at left. (About one and one-third times natural size.) sexual character the male molts once (sometimes twice) before attain- ing maturity, at which time the web is abandoned and his search for a mate begins. The female takes longer to mature and has an average of seven molts, with a range of from six to eight. When preparing to molt nothing is eaten for several days. The old skin splits around the margin of the carapace, slips off the abdomen, and the spider then gradually pulls its legs free from its old sheaths, leaving the "ghost" of itself on or nearby the web. The entire process requires about an hour. The newly molted spider (fig. 4) is rather delicate and usually remains at rest for a day or so after molting. Individuals occasionally die during the molting process. 12 University of California — Experiment Station DESCRIPTION OF THE IMMATURE STAGES First Instar. — The abdomen of the newly hatched spiderling (fig. 5) is opalescent white with no markings. The cephalothorax and append- ages are white to pale yellow; short hair covers the body, becoming dark at the tips of the legs. The tarsi, or last segment of legs, have two notched claws and a supplementary third between. Eight simple eyes are on the an- terior margin of the cephalothorax in 2 rows of four, and the anterior medians are comparatively dark. Second Instar (fig. 6). — All eyes be- come darker and a black band extends down the center and around the margin of the carapace. Also the mouth parts and the appendages become darker as well as the margin of the sternum of the cephalotho- rax. A double row of black dots extends down the mid-region of the dorsum of the abdomen which remains whitish. On the underside of the abdomen the white area takes on a broad hourglass de- sign outlined by a dark-brown border. Fig. 5. — Newly hatched (first instar) black widow spiderlings. (About seven times natural size.) Fig. 6. — Immature black widow spider of second instar: A, ventral view B, dorsal view. (About three times natural size.) Third Instar. — From this stage to maturity a wide variation in color pattern occurs. Distinct lateral stripes begin to appear on the dorsum of the abdomen, in the region of the dots of the second instar. Inter- vening areas take on a pale greenish-yellow cast, and the legs acquire Bul.591] Black Widow Spider 13 four black bands, one at each end of the patella, one near the center of the tibia, and one at the junction of the tibia and the metatarsus. The longitudinal white area on the underside of the abdomen becomes tinged with crimson. Fourth Instar. — Dark stripes or bands become distinct and faintly bordered with buff. The spinnerets take on a mottled appearance. Black bands at the leg joints become more distinct (fig. 7). Fig. 7. — Immature black widow spider of fourth instar: A, ventral view; B, dorsal view. (About three times natural size.) Fifth Instar. — The central dorsal white stripe on the abdomen tends to be constricted at intervals and acquires a reddish tinge near the tip. All white areas become lightly colored with brown. Males usually ma- ture at this point. Sixth and Seventh Instars. — Usually only the females go through these two stages. All coloration is much darker and the more variable remaining white areas become more and more restricted. Often a series of reddish spots are formed along the middorsal region of the abdomen (fig. 8). Eighth Instar. — Only the females pass through this stage, which is often difficult to distinguish from the mature form. They are usually all black or sepia with the exception of the characteristic crimson mark- ings and an occasional white band on the anterior margin of abdomen. ( See description of mature female, page 4. ) 14 University of California — Experiment Station LONGEVITY The length of life of individual spiders, as one might expect, varies with such factors as food supply, natural enemies, including man, etc. Under optimum conditions of food, temperature, humidity, etc., the complete life cycle from egg to maturity requires at least four months. Spiderlings emerging from eggs laid in July and hatched in August will, of course, pass the winter in an immature stage which thus ma- terially extends the length of time required to complete the life history. Activity on the part of both the spiders and the insect prey is greatly Fig. 8. — Immature female black widow spider at the sixth or seventh instar: A, ventral view; B, dorsal view. (About two times natural size.) reduced during the winter months and thus largely accounts for the retardation in development. When a brood emerges in late spring or early summer the females generally reach maturity before cold weather sets in but egg laying is held over until the following spring, and hence the life cycle is extended over a complete year. Mature males have not been found overwintering. Under laboratory conditions a few females have lived through the second and third summers, giving a life span of nearly two years. Bul. 591] Black Widow Spider 15 VENOM APPARATUS Spiders are equipped with a poison apparatus for purposes of kill- ing their prey. The venom apparatus of Latrodectus mactans consists of two poison sacs each with an attached duct leading into the heavily chitinized chelicerae (horny fangs) from which the poison is expelled at the time of biting. The venom apparatus is present in both the male and the female spider. In the male the venom is of use in the immature stages only. Since the mature male does not attack prey the poison apparatus appears to become inactive and remains small in size. In the Fig. 9. — Chelicerae (fangs) of black widow spider with poison sacs attached. A, female; B, male. (Fifteen times natural size.) case of the female spider, on the other hand, the venom apparatus in- creases in size and strength with maturity. The quantity of the venom present in the large poison sacs of the female black widow spider makes her presence perilous. The poison sacs of the mature female (fig. 9 A) average about 0.40 millimeter in diameter and 2.70 millimeters long, and in the mature male (fig. 9B) they average 0.16 millimeter in diam- eter and 0.66 millimeter in length. The poison sacs are located in the cephalothorax extending posteri- orly about two-thirds of the way to the junction of the cephalothorax with the abdomen. The long narrow sacs curve outwardly around the fovea media, that is, the indentation in the center of the cephalothorax for muscular attachment; this is due to the position of the sucking stomach directly below. If the poison sacs were over the sucking stomach they would be squeezed together every time the sucking stomach filled 16 University of California — Experiment Station with food and cause a loss of venom. In the female (all stages) the poison sacs are opaque and filled with venom, while in the mature male they are translucent and devoid of venom. NATURE OF THE VENOM There is good evidence that the poison sacs are not glandular in na- ture but function as absorptive organs which take up the poisonous constituents from the body fluid of the spider. Sachs (1902) and Kobert in 1901 and 1906 (according to Bogen, 1926) isolated from the spider body a specific poisonous principle named "arachnolysin" which they claim has a hemolytic effect on blood of various animals (see also Hall and Vogelsang, 1932) . Our evidence relative to the venom of Latrodectus mactans indicates that it is a neurotoxin. Spider poison is not limited to the poison glands, but is also carried in the body fluids as pointed out by Sachs and by Kobert. Blyth and Blyth (1920) in their book on poisons write : The Kara-Kurt of the Tartars = "black wolf" is Latrodectus lugubris, common in south Russia, and attaining a length of 2 centimeters [% inch]. The Kara-Kurt poison is not only found in special glands, but is also diffused through the body. Kobert investigated this poison and stated that it is a generic type of the poison of spiders, the active principle is neither a glucoside, acid, nor an alkaloid. It does not dialyse, and drying destroys its activity ; it has the characters of a toxalbumin, and has much similarity to the action of ricin and abrin. The Kara-Kurt poison dis- solves the coloring matter of the red blood corpuscles even with a dilution of 1: 127,000; it has a paralyzing effect on the heart, either due to action on the motor ganglia, or, possibly a direct action on the muscle itself. The blood pressure sinks, the walls of the smallest arteries and capillaries become so changed as to allow the transudation of the blood and serum, producing punctiform hemorrhages and edema. This is best seen in the lungs. . . . The poison also has a paralyzing action on the central nervous system, but it is not clear whether this action is primary, or whether it depends on the circulation troubles. The fatal dose of the poison, injected subcutaneously or intravenously, is ex- tremely small. Cats are killed by quantities equal to 0.2 to 0.35 milligram per kilo- gram body weight. Repeated injections of nonfatal doses confer immunity. Kellogg (1915) states that high temperatures destroy the action of extracted black widow spider venom. It can withstand a temperature of 56° Centigrade (132° Fahrenheit) for 40 minutes, but is wholly de- stroyed if heated for 45 minutes at 70° Centigrade (158° Fahrenheit). The venom cannot be crystallized, since it is destroyed by desiccation. The best means of preserving the extracted venom is in glycerine, where it can be kept for several months. Bul. 591] Black Widow Spider 17 LABORATORY EXPERIMENTS Kellogg (1915), experimenting with rabbits and cats, found that the dissected glands of one female Latrodectus mactans macerated in 10 drops of distilled water, then injected subcutaneously into the abdomen of a cat, about eight months old, was followed by the death of the animal in 10 minutes. A second dilution was made by macerating a pair of poison glands in 10 drops of water and diluted to 100 cubic centimeters. Ten drops of this were injected into the abdomen o ; f an eight-months-old cat, death following in 45 minutes. These experiments show the great potency of weak dilutions of the hemolysin when injected into suscep- tible animals. Extracted poison introduced into vials containing whole blood of rabbits and other susceptible animals destroys the corpuscles. Thus arachnolysin is in the class of the strongest kind of blood poisons. Kellogg (1915), in reporting the work of Coleman, cites experiments in which the poison sacs of a female black widow were cut out and the contents macerated in 10 drops of distilled water, then 100 grains of pure sugar of milk were added and the whole triturated for 10 minutes. To this were added 90 grains of fresh sugar of milk and triturated, which thus gives 1/1000 grain of the poison in each grain of the sugar of milk. Coleman made powders containing 2 grains of this mixture, or 2/1000 grain of poison per dose. After taking 10 of these powders orally at intervals of 1 hour, the only symptom Coleman noticed was a de- crease in the heart beat. When 20 powders had been taken the heart rate was 54, the occipital pain was severe, with cramping pains in chest and abdomen, the pupils were dilated, and there was some distress about the heart. When 25 powders had been taken the heart rate was 48, tem- perature 99° F and great distress was felt about the heart. Coleman considered this a perfect picture of angina pectoris. In 3 days the symp- toms completely disappeared. The experiment was repeated three times with the same result. Coleman later administered a 2-grain powder of the above mixture to a patient suffering from angina pectoris and in 10 minutes the attack passed away. This trial was not repeated owing to the death of the patient when taken with another attack while out of reach of medical aid. In reporting on experiments in which white rats were used Baerg (19236) states: . . . white rats about four weeks old were used. The difficulty that several investi- gators have met, when trying to induce the spiders to bite, was overcome by feed- ing the spiders about 48 hours before the tests were to be made. Although, by ob- serving this rule, all our attempts to induce the spiders to bite met with success, yet it seems very doubtful that this is the real or only reason for the results. By 18 University of California — Experiment Station making a considerable number of tests one obviously acquires some little ability in holding the spiders properly, and this is perhaps more important in getting the desired response from the spiders than is the particular day of feeding. The rats were prepared for the test by clipping off the hairs on the inside of the left hind leg. Two rats and two spiders were used in the first test. The spiders bit well and the fangs were allowed to remain inserted for several seconds. In a short time both rats presented distinct symptoms of illness. They humped up, turning their heads underneath till the faces rested on the floor of the cage; from time to time they would jerk forwards as if in convulsions. The eyes were usually closed and the rats were not easily aroused. When walking they were un- steady and stumbled frequently. These effects lasted from 6 to 10 hours, when the rats rapidly recovered and behaved in an entirely normal manner. To confirm these observations the test was repeated, applying the same spiders to the same rats. The symptoms were very similar to those following the first test, but markedly milder. Concerning acquired immunity of rats to spider venom, Baerg (19236) reports: In view of the fact that the rats exhibited milder effects after the second test than they did after the first, it seemed well to make additional tests and determine how readily the animals became immune to the effects of the poison. The same rats that were used in the test described . . . were used here. When these rats had been bitten for the third time, they showed rather slight effects too of poisoning. After the fourth time, the rats showed no other response than licking the bitten leg. These tests were made at intervals of one week. A degree of immunity that is well-nigh perfect is thus acquired by the rats when they have received three rather large doses of the poison. Bogen (1926) conducted experiments with this spider on white rats because of the various reports recorded on experimental studies on the bites of Latrodectus modems. He writes : .... Eepeated injections of macerated suspensions of Latrodectus macians, as well as solutions of the expressed poison glands were made in a number of animals, in- cluding rabbits, chickens, cats, and white rats, without noticeable effect. There was no evidence of any hemolytic effect either in the tissue extract or the suspension of the poison gland as tested against the blood corpuscles of rabbit, sheep, and man. The bite of the spider, however, produced the definite symptoms described by Baerg in a young rat, as may be illustrated by a report of a typical experiment. Bogen (1926), working with white rats as experimental animals for Latrodedus madans bite, concludes : There is a peculiar, striking and characteristic chain of symptoms following the bite of Latrodectus mactans, a poisonous spider common in North America. An ex- haustive examination of the available literature on poisonous spider bites in all corners of the earth and an analysis of 150 cases that have been reported in the United States have been attempted. The experimental studies previously made have been reviewed, and additional experiments performed to elucidate some of the moot points. Constant characteristic symptoms have been produced by the bite of a young white rat. It is concluded that the foregoing warrants the acceptance of arachnid- ism, or spider-bite poisoning, as a true clinical entity in the field of general medicine. Bul. 591] Black Widow Spider 19 In 1933 and 1934 animal experiments were conducted at the Univer- sity of California using guinea pigs and rats. The experiments with white rats showed that these animals are not highly susceptible to this venom. The rats were affected but little by the bite of the black widow. They showed nervousness — scratching the floor of the cage and run- ning about aimlessly, sneezing, and scratching their bodies. When sleep- ing their heads were drawn under their bodies to rest on the floor. The morning of the second day the rats were normal. When the work with the rats proved unsuccessful as a means of studying the effects caused by the spider poison, guinea pigs were introduced into the experiments. The guinea pig proved a more susceptible animal and the following experiments were conducted on them. Fig. 10. -Glass tube for holding spiders in laboratory tests on animals. Guinea pigs of various ages were used in these experiments. The spiders used were adult female Latrodectus madam, some before the spinning of the first egg sacs and others after they had spun from one to three egg sacs. The fallacious idea prevails that the black widow is a vicious spider which will pounce upon one's person and inflict a bite without cause. The black widow is a shy spider and seeks dark places where it is less apt to be disturbed. Because of this characteristic it was difficult to induce a bite on the animals used in the laboratory. Some individuals will bite more readily than others and these remain so no matter how often they are used. The period of starvation before using a specimen to inflict a bite has little influence on the readiness to bite. The handling of the spiders was made relatively simple by the use of a glass tube about 3 inches long and % mc h in diameter, one end of which was plugged with a cork, through the center of which was in- serted a large flat-headed bolt. The bolt was used to control the position of the spider in the tube (fig. 10) . In some experiments when one person was working alone the guinea pig was placed in a wire cylinder with a 20 University of California — Experiment Station small door on one side through which the animal's hair could be clipped and the tube containing the spider inserted (fig! 11) . Guinea pigs weighing from 250 to 500 grams are killed by the black widow venom in from 1 hour and 45 minutes to 4 hours. The first symp- toms develop about % minute after the bite. A marked excitation of the motor nerves occurs. Sneezing and coughing are the first respiratory symptoms, increasing in violence and frequency until they take the form of respiratory spasms. The abdomen becomes distended and convul- sions set in. The area of the bite takes on a purplish color. Breathing becomes difficult with an exudation from the nasal and buccal passages. The diaphragm becomes tense and apparently paralyzed. The tempera- _j - he I l ifffitri n rinf nm Fig. 11. — Cage for holding experimental animals, showing door for insertion of tube containing spider. (See figure 10.) ture remains normal and the heart beat slow until the fatal paralysis of the respiratory system is complete, when the heart beat is rapid and faint. Death occurs in a convulsion. Post-mortem examinations showed the stomach wall ruptured in two out of five cases, the small intestines being filled with a bloody fluid, and the diaphragm contracted and rigid. The liver was normal, the heart walls showed dark areas, blood clots other than "chicken fat" were pres- ent in the heart and large blood vessels. The lungs contained a multi- tude of minute hemorrhages. Experimentation showed that cutaneous bites are of little conse- quence save for local swelling and irritation. Subcutaneous bites, on the other hand, prove fatal to guinea pigs. One spider was allowed to bite three different animals in succession at intervals of 1 hour. The first animal died in less than 2 hours; the second animal became ill but re- covered in 2 days; the third showed no reaction to the bite save for an occasional sneeze during the first 24 hours after the bite. It would seem Bul. 591] Black Widow Spider 21 from the above that the spider is slow in refilling the poison sacs and that the first bite inflicted contained most of the venom, which perhaps shows the reason for negative results of some workers. The second and third animals in this experiment were used for further work. One week after the first bite the second animal was allowed to be bitten again and showed no symptoms of illness; one month later the same animal was bitten a third time and showed slight reaction to the venom. During this period the skin on the underside of the abdomen sloughed off 2 inches on either side of the first bite. The third animal died during a heart bleeding to obtain blood for convalescent serum. Convalescent serum made from the pooled bloods of the second and third animals was inoculated into two other animals, one before it had been bitten and the second after respiratory paralysis had set in. The first of these animals was bitten 1 hour after the administration of the convalescent serum; this animal died 12 hours later from pneumonia. The second animal to receive serum died 17 hours later. EFFECT OF BITE ON MAN The chain of symptoms resulting from the bite of the black widow spi- der is so striking that once recognized there is little danger of confusing it with other venomous forms or an acute surgical abdominal condition. Cases of arachnidism, or spider-bite poisoning, have been incorrectly diagnosed by those unfamiliar with the symptoms as a ruptured gastric ulcer, acute appendicitis, renal colic, tabetic crises, tetanus, and food poisoning. Abdominal incisions and post-mortems have revealed the in- testine to be contracted nearly to the size of a lead pencil, resulting in a paralytic ileus. The bite itself (similar to a pin prick) is not always felt and often there is but little evidence of a lesion. However, a slight local swelling and two tiny red spots may occur, and local redness is usually in evi- dence at the point of attack. Pain, usually in the region of the bite, is felt almost immediately and increases in intensity, reaching its maximum in 1 to 3 hours and gen- erally continuing for 12 to 48 hours, gradually subsiding. A rigidity and spasm of most of the larger muscle groups of the body (particu- larly the abdomen) are most notable. The abdominal muscles become "board-like," but local tenderness as in appendicitis is almost always ab- sent. There is a slight rise in body temperature, increased blood pres- sure, and also, as Bogen (1932) reports, a definite leucocytosis, that is, an increase of number of leucocytes in the blood, and usually an increase in the pressure of the spinal fluid. A profuse perspiration is evident and often a tendency to nausea. The degree with which such symptoms are 22 University of California — Experiment Station present varies in individual cases, and other symptoms such as chills, urinary retention, constipation, hyperactive reflexes, priapism, and a burning sensation of the skin are frequently reported. Baerg (1923a), who permitted himself to be bitten (basal joint of the third finger of the left hand) by the black widow spider, when reporting on the effect of the bite, states : Referring briefly to some of the general effects of the case, I would say that the sharp pain in the finger, or rather in the left hand, was the most prominent feature. Very nearly as unpleasant was the aching pain which was most violent in the thick muscles of the lower part of the back, and present in almost all the muscles of the shoulders, chest, and legs. There was no marked tendency towards profuse perspira- tion. I sweated heavily only when I first went to bed, and later after each one of the hot baths. I covered up well after these baths in order to bring about sweating, and I believe that it aided in recovery. There was no evidence of constipation. One dose of magnesium citrate brought fairly prompt results. On the day I left the hospital, 1 took a second dose, in order to facilitate recovery as much as possible. Baerg's physician, Dr. E. F. Ellis, added the following note : The subjective symptoms in Mr. Baerg's case have been very graphically described by him. The objective symptoms would indicate, as observed by me, that there is a very marked phagocytosis locally around the area of the spider bite. The toxicity of the bite was such that the phagocytes very shortly offered no resistance to the systemic invasion of the poison. The poison in my opinion was partly transmitted through the blood stream and partly through the nerve trunk which in this case was the median nerve. Strange to say in this particular instance the patient had a marked vasomotor disturbance on the flexor side of the forearm, as was evidenced by a narrow strip something like an inch in width, extending up almost to the elbow in which there was very marked diaphoresis. This was present during the first 24 hours after the bite. The toxicity was also manifested by vasomotor changes in the lumbar muscles and muscles of the extremities, and in all the large joints of the body, as was shown by intermittent pains and symptoms similar to intermittent claudication. There seems also to be a disposition, on his part, to unload very slowly, by elimination, the prod- ucts of poison. More so than is the case witli bites of any of the snakes including the rattler that I have observed. CLINICAL CASE RECORDS The following case records from the Woodland (California) Clinic are typical of arachnidism : n at i Age: 41 Sex : Male Nationality : Dutch Occupation: laborer Date admitted: 9-3-31 Date dismissed: 9-8-31 9-3-31. About 8:30 p.m. on September 3, patient was taken with a sharp pain in the glans penis as he was sitting on the stool of an open privy. In about 15 to 20 minutes the pain spread to the abdomen, hips, and thighs, the pain being steady, deep, and dull, and so severe that the patient doubled up and rolled on the floor. His abdomen got hard with the onset of the pain. In about 2 hours pain had developed in the back. He was given two hypodermics (morphine) on entry which relieved him some but stated that he slept only y 2 hour during night. Heat was applied to legs and back. Around 4 this morning (9-4-31) the pain seemed to shift to legs (below Bul. 591] Black Widow Spider 23 knees) and feet. In addition to type of pain described in the abdomen, he had an in- tense burning sensation of the skin, worse on soles of the feet. Patient has slight pain in chest, no appetite, and feels weak and shaky all over. Patient unable to urinate. 9-4-31. Patient now has pain in back and legs. Sweating profusely. Pulse, 80. Ab- domen absolutely rigid — "board-like." Legs flaccid, neck not stiff. Examination of penis reveals old scars, no recent lesion seen. Impression — arachnidism. 9-5-31. Pain practically gone. Voiding and eating well. 9-7-31. Free of pain. Except for weakness, feels well. 9-8-31. Free of pain. Feels well. Dismissed. Chart shows patient's temperature fluctuated but not abnormally, pulse somewhat above normal, and respiration normal. Case No. 2 Age: 24 Sex: Male Nationality: American Occupation: laborer Date admitted: 6-17-32 Date dismissed: 6-31-32 6-17-32. About 9 p.m. last evening patient retired and after getting in bed some- thing dropped on his right shoulder. After turning on the light he discovered a large jet-black spider which he killed. About midnight he noted a tightness in his abdo- men and a rather severe lumbar backache. Went to a local physician who gave him a hypodermic about 2 a.m. Abdominal tenseness and pain increased and patient be- gan to note leg pain. 6-17—32. Patient admitted at 3:30 a.m. and examined. Eight hundred cubic centi- meters of 5 per cent glucose in normal saline given intravenously after which pulse, which was thready, became fuller and stronger. At 4:45 a.m. considerable back pain and given morphine sulfate (% grain). 6-18-32. Abdomen softer. Considerable pain in feet. Profuse perspiration — now apparently out of danger. 6—20—32. Abdomen soft, eyelid edema gone. Considerable discomfort in both feet. Still perspiring but reduced. 6-31-32. Patient discharged. Fingernails look blue. Chart shows patient's temperature to be slightly above normal, pulse fluctuating, and respiration normal. The data shown in table 1 (including the above cases) have been com- piled from 37 case records of arachnidism during the last ten years at the Woodland (California) Clinic. Of the total number of cases, about one-half were bitten on the genitalia while using an open privy. Four of the cases were female patients and the remainder males, the majority of which were laborers and farmers between the ages of twenty and fifty. Five school children were among those treated. The temperature and pulse of the patients were usually slightly above normal, and the respira- tion normal. Morphine sulfate (% grain) was employed in 25 cases and other drugs such as codeine, amidopyrine, atropine, hyoscine, etc., in the remainder. There was no correlation between the time of day and the bites. The spider was seen in 11 cases. None of the patients reported any after effects on the follow-up inquiry by the attending physician. 24 University of California — Experiment Station Only two deaths were reported in these records, one (6-25-24) a male of seventy-eight years with heart and syphilitic complications and the other (7-13-25) also a male (an itinerant) of forty-four years who died 4 days after being bitten. Post-mortem examination of the latter case showed a ballooned intestine and the patient was recorded as dying of a paralytic ileus resulting from a black widow spider bite. TABLE 1 Incidence of Gases by Years, Months, and Age Groups Incidence of cases by months Incidence of cases by years Incidence of cases by ige groups Months Number of cases Years Number of cases Age group Number of cases 1 1 1 7 11 7 5 2 2 37 1924 3 3 4 1 6 7 5 6 2 37 0- 9 1925 1926 10-19 20-29 10 April 1927 30-39 May 1928 40-49 11 1929 . . 50-59 1930 60-69 1931 1932 1933 1934* 70-79 September 37 December * Data for 1934 is incomplete. An examination of table 1 (only hospitalized cases) shows the great- est number of bites during June, July, and August, although cases were admitted to the hospital (Woodland Clinic) every month in the year except December, January, and March. Table 2, showing incidence of deaths in California for 1930^-1934, inclusive, includes a death from "spider bite" for March, which thus leaves only December and January when no bites are recorded. TREATMENT When bitten by the black widow spider, the patient should be treated with local antiseptics, such as tincture of iodine, at the point of injury to prevent secondary infection, kept as quiet as possible, and a physician summoned at once. Contrary to the popular belief that the treatment should be the same as for rattlesnake bite, cauterization, the use of a tourniquet, etc., are not recommended by the best medical authorities. Since, among other prop- erties, the venom appears to be neurotoxic and its effect little short of instantaneous, such first-aid measures are of little value. Bul. 591] Black Widow Spider 25 Professional treatment ,f or the bite of the black widow spider consists mainly in the use of opiates, hydrotherapy, and similar measures to alle- TABLE 2 Incidence of Deaths by Years, Months, Age Groups, Sex, and Locality for 1930-1934,* Inclusive Year Month Age Sex Locality Cause of death Other contributory causes 1930 2 Taft 1931 69 1931 June 43 Male Brawley Black spider bite Toxemia 1931 August 29 Male Modesto Black spider bite 1932 May 18 Female Montrose Spider bite of forehead Staphyloccus cellulitis face and scalp 1932 August 26 Male El Centro Spider bite Periurethral abscess 1932 August 60 Female Merced Poison bugf bite Septicemia 1932 September April March 69 Male Spider bite 1933 62 Male 1934 1 Male Brawley Spider bite of right arm Infection of right arm, otitis-media, septice- mia 1934 February 29 Male Los Angeles Spider bite Acute cellulitis, left cheek and neck; secondary abscesses both lungs 1934 May 71 Female Los Angeles Insectf bite on ankle Acute cellulitis of leg and thigh; cirrhosis of liver 1934 July 41 Female Loma Linda Insect bite, probably spider Staphyloccus infection face; septicemia * Data from death certificates of the California State Department of Public Health compiled by us from files in the possession of T. I. Storer. f Probably spider bite. viate the acute pain. Medical records according to Bog-en (1926, 1932) list more than seventj^-five different remedies and of all these, three seem to be outstanding as palliatives : namely, spinal puncture, intravenous injections of magnesium sulfate (10 cubic centimeters of a 2 per cent solution — see Bogen, 1932, and De Asis, 1934), and intramuscular ad- ministration of convalescent serum when given within 8 hours. However, until more evidence on controlled cases is at hand, the question as to which method is the best remains an open one. Also, individual cases vary greatly and exhibit much inconsistency in their response to treat- ment. As Bogen (1932) states, in part ". . . despite its severe symptoms, arachnidism is, in the majority of cases, a self -limited condition, and generally clears up spontaneously within a few days." CONTROL In localities experiencing mild winters the black widow spider popu- lation increases steadily, particularly because of the tropical and sub- tropical nature of the species. Where the winters are long and cold few 26 University of California — Experiment Station black widow spiders are able to overwinter, and the population in these areas remains more or less stable. As stated previously this spider is found in sheltered situations in and about man-made structures or in similarly protected places in the field. The black widow is frequently found in garages, basements, in living quarters, in old outbuildings, par- ticularly privies, old barns, stables, and woodpiles. Workers in dried- fruit industries find numerous black widow spiders under the drying trays when turning the trays. In the open the spiders inhabit vacant lots and hillsides, building their webs in crevices of rocks, between ad- jacent rocks, under logs, under projecting banks, in deserted squirrel or rabbit holes, under low wooden or concrete bridges, culverts, etc. Owing to the wide distribution, solitary habits, and varied habitat of the black widow spider, great difficulty is experienced in control. It is necessary to determine at what stage in development control can be most effectively applied. Since the egg sacs are conspicuous and are not carried about by the spider, they may be readily collected and destroyed. Great care should be exercised when collecting egg sacs because the fe- male spider guards the sac closely and is particularly pugnacious at that time. The public should be encouraged to collect and burn or other- wise destroy the egg sacs of the black widow spider. Where accessible, the adult spider can be brushed from its web with a broom or stick and stamped upon, or a suitable insect spray may be used to cause the spider to fall to the floor where it should then be crushed. The spider will al- most always recover from the effects of a fly spray; hence it should be crushed or otherwise destroyed. The use of a blow torch when no hazard is involved is effective in the destruction of eggs and adult spiders as well. Because of the danger from spider bite when using privies in rural sections, it is suggested that the undersides of the seats and corners of the box be painted well with creosote or crude oil. The adult female black widow spider is extremely difficult to kill with any contact spray. The common fly sprays act for the most part as mod- erate repellents, and, at best, only render the spider temporarily para- lyzed. Of such chemicals tested as carbon tetrachloride, carbon bisulfide, and a combination of ethylene dichloride and carbon tetrachloride, the first appears the most effective and paralyzes the spider almost imme- diately. However, in a few hours normal activity returns. A 1 per cent solution of nicotine sulfate in water will usually kill the spider if thor- oughly drenched with the spray, but this is not always possible because of the spider's habit of withdrawing into protected quarters when dis- turbed. Pyrethrum-oil spray used at full strength has no immediate effect but gradually the spider becomes paralyzed and will often remain so for several days, eventually recovering in most cases. Creosote, used Bul. 591] Black Widow Spider 27 as a spray, has proved to be the most effective material yet employed and, if the spider is contacted, death has resulted in every case observed. In addition to killing the spider, the creosote acts as a repellent. The immature spiders are much more readily killed than the adults and most of the above-mentioned chemicals are usually effective. Dusts are not considered so satisfactory as sprays. The control of the black widow spider by the use of its parasites or predators (biological control) can be regarded at present as only a re- mote possibility, largely because of the isolation of individuals and wide- spread distribution of the species and particularly because of difficulties Fig. 12. — A, Adult dipterous (fly) parasite (family Clilorop- idae) ; B, pupae on shriveled egg sac. (Fly about six times nat- ural size, and pupae about two times.) in mass production of the parasites. Three natural insect parasites of the black widow are known to us, two hymenopterous (wasps) and one dipterous (a fly). Dozier (1931) working at Port-au-Prince, Haiti, de- scribed an egg parasite (a wasp belonging to the family Scelionidae) of the black widow spider. The new species described by Dozier was named by him Baeus latrodecti. This appears to be a true egg parasite, a single larva destroying a single egg; therefore, the complete brood in an egg sac is not destroyed and some spiders hatch, only partial control being achieved. We have not found this parasite in California. One of the authors working at Davis, California, found a dipterous parasite (family Chloropidae) of the egg sac of the black widow (fig. 12). The species as yet undescribed has also been found near San Jose by L. R. Cody, at Ventura by Rodney Cecil, and also in Berkeley and on Mt. Hamilton by one of the authors. This is a predator feeding on the spider eggs within the sac (fig. 12) and is known to destroy the complete brood. Attempts to rear this parasite in the laboratory have so far failed 28 University of California — Experiment Station apparently owing to the inability to mate them under artificial condi- tions. Work on this predator is being continued. A wasp-like parasite of the genus Gelis (fig. 13) was discovered by one of the authors on Mt. Hamilton and was reared from egg sacs taken Fig. 13. — Gelis sp., a wasp-like (hymenopterous) parasite of the black widow spider; feeds on eggs in egg sac. A, male; B, female. (Four times natural size.) in the field and transferred to the laboratory at the University of Cali- fornia at Berkeley. This is also a predator in the larval stage (fig. 14) Fig. 14. — A, Larvae of wasp-like parasite (Gelis sp.) among the eggs of the black widow spider. B, Egg sac torn open to show pupae of the parasite. (Two times natural size.) on the eggs in the sac and completely destroys the brood. It is also an undescribed species. Research on this predator is being conducted and the second generation is now on hand. Bul. 591] Black Widow Spider 29 LITERATURE CITED Baerg, W. J. 1923a. The effects of the bite of Latrodectus mactans Fabr. Jour. Parasitol. 9: 161-169. 1923ft. The black widow: its life history and the effects of the poison. Sci. Mo. 17:535-547. 1929a. Some poisonous arthropods of North and Central America. Fourth Inter- nal. Cong. Ent. 2:418-438. 1929&. The black widow. Nature Mag. 14:152-154. Blyth, A. W., and M. W. Blyth. 1920. Poisons: their effects and detection. 5th ed. 745 p. Chas. Griffin & Co., Ltd., London. BOGEN, E. 1926. Arachnidism. Arch. Int. Med. 38:623-632. (Contains a bibliography of 462 titles.) 1932. Poisonous spider bites: newer developments in our knowledge of arachnid- ism. Ann. Int. Med. 6:375-388. Brown, C. W. 1895. Poisonous spiders of southern California. Southern California Practitioner 10:451. Browning, C. C. 1901. Original investigations of spider bites in southern California. Southern California Practitioner 16:291-300. Comstock, J. H. 1914. The spider book. 721 p. Doubleday, Page and Co., New York. De Asis, Cesares. 1934. Red back spider bite and magnesium sulfate treatment. (A clinical study of four cases.) Amer. Jour. Trop. Med. 14:33-44. Dozier, H. L. 1931. A new scelionid egg parasite of the black widow spider. Ent. Soc. Wash. Proc. 33:27-28. ESCOMEL, E. 1917. The Latrodectus mactans and the Gliptocranium gasteracanthoides in the Department of Arequipa, Peru. Amer. Soc. Trop. Med. Trans. 2:95-108. Fabricius, J. C. 1775. Systema Entomologica sistens insectorum classes, ordines, genera, species, etc. 2:410. Flensburgi et Lipsiae, Korte. Hall, W. W., and W. A. Vogelsang. 1932. Spider poisoning: a study of the toxin of the black widow spider (Latro- dectus mactans). U. S. Naval Medical Bul. 30:471-478. Herms, W. B. 1923. Medical and veterinary entomology. 2nd ed. 462 p. Macmillan Co., New York. Kellogg, V. L. 1915. Spider poison. Jour. Parasitol. 1:107-112. Lawson, Paul B. 1933. Notes on the life history of the hour-glass spider. Ann. Ent. Soc. Amer. 26:568-574. 30 University of California — Experiment Station Merriam, C. H. 1910. The dawn of the world (Indian tales). 273 p. A. H. Clark Co., Cleveland. Petrunkevitch, A. 1911. A synonymic catalog of spiders. Bui. Amer. Mus. Nat. Hist. 29:181, 757. Eau, P. 1924. Some life history notes on the black widow spider, Latrodectus mactans. Psyche 31:162-166. Eiley, C. V., and L. O. Howard. 1889-1894. Correspondence and discussions of spider bites. Insect Life 1:204- 211, 280, 313, 347; 2:46, 47, 75, 134, 273; 3:30, 129, 178, 337, 392, 425, 487; 4:277; 6:52; 7:276. Sachs, H. 1902. Zur Kenntniss des kreuz Spinnengiftes [To the knowledge of the venom of cross spiders]. Beitrage zur Chemischen Physiologie und Pathologie [Con- tributions to chemical physiology and pathology] 2:125-133. Wade, W. L. 1889. Spider bites. Southern California Practitioner 4:344. 18m-6,'35