CALIFORNIA AGRICULTURAL EXTENSION SERVICE CIRCULAR 63 April, 1932 CODLING-MOTH BAIT TRAPS ARTHUR D. BORDEN Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA Digitized by the Internet Archive in 2011 with funding from University of California, Davis Libraries http://www.archive.org/details/codlingmothbaitt63bord CODLING-MOTH BAIT TRAPS 1 ARTHUR, D. BORDEN-' INTRODUCTION That the codling- moth (Carpocapsa pomonella Linn.) is attracted to vinegar, cider, and other baits was apparently noted early in the economic history of the insect in America, probably prior to 1850. Numerous reports of the success of growers appear in the farm and horticultural publications of the quarter century after 1850, though investigators continued to condemn the use of baits. In 1922-23 considerable interest was aroused in the Pacific Northwest as a result of the success reported by a grower and similar interest was taken in the east in the success of a grower with baits at Hagertown, Maryland. It was apparently not until 1924 that success was reported in trapping codling moths over a period of several years. Apple mash and 10 per cent vinegar were used as a bait, and a later success with cider, molasses, and chemical attrahents leds other investigators in the Pacific Northwest and the Midwest, and in Australia, to take up the work. The success of the bait traps in the Pacific Northwest and in other fruit districts has given an impetus to the use of this auxiliary means of control, and at present it is accepted as an accurate, standard method in timing moth emergence. In the investigation of apple insects in California during the past five years, the control of the codling moth has been a major project, and the practical use of the bait traps has been demonstrated. The moths are attracted in large numbers to bait traps properly placed, and the daily catch as the season advances gives the orchardist a key to the proper timing of spray applications. As a means of deter- mining the emergence of the moths these traps are much more accurate and convenient than burlap banding, wire cages, and pupa blocks, which were formerly used. The total catch of moths in 10 pans at Sebastopol, California, is given in table 1. i The writer is indebted to Dr. Ralph H. Smith for calling his attention to early references on bait traps, and to Mr. Alfred Hallberg and Mr. O. E. Libby of Sebastopol for their assistance in keeping codling-moth emergence charts during the progress of the investigation. 2 Assistant Entomologist, University of California Agricultural Experiment Station. California Agricultural, Extension Service [Cm. 63 TABLE 1 Total Catch of Moths in Ten Pans, Sevastopol, California, 1928-1931 1928 1929 1930 1931 Month Days Moths Days Moths Days Moths Days Moths 5 31 30 378 339 151 5 31 30 130 1,211 508 16 31 30 1,244 811 460 25 31 30 697 922 203 Total, May to 66 868 66 1,849 77 2,515 86 1,822 July * 31 31 30 24 281 418 118 75 31 31 30 20 370 853 677 82 31 31 25 567 807 105 Total, July to 116 893 112 1,982 87 1,479 N No record was kept from July to October, 1928. Bait traps do not eliminate the necessity for spraying, but are used primarily as a more accurate means of determining the time for making the applications. With a sufficient number of pans in an orchard it is entirely possible that the moth population could, in several years' time, be considerably reduced, for more than 50 per cent of the moths taken are females and over 90 per cent of these females are with eggs. Whether bait trapping over an extensive area would be practical from a cost standpoint depends upon the number of moths taken and the cost of operation. In comparatively light infestations this plan has not been practical. Most growers in California time their spray applications by cal- endar dates or by certain stages of development of the fruit, which is at best uncertain, for it often does not agree with the appearance of the moths, The time of emergence varies greatly from one season to another, and a spray program which proved satisfactory one season may not be at all adequate or properly timed for the next season. This is well illustrated in the bait-trap records of the first brood of moths in the Sebastopol district for the years 1928 to 1931 (fig. 1). A single application early in May in the year 1928 proved adequate for the first brood, while in 1929 and in 1930 three applications properly timed were required, and in 1931 two applications. Growers who trusted to the usual two spring applications in 1929 and 1930 lost heavily from worms, while orchards sprayed according to the bait-trap records had a minimum loss. 1932 Codling-Moth Bait Traps Moths per w 5 oi o vi pan o > q o w o o tfi 5 5 r c- : BBfcf ' Br , > < N O Ft HL. 5 w o o 5 o, u o o 1 c ,::,■ cL. / IP 1 "fe, I 01 o w 6 California Agricultural Extension Service [Cm. 63 Again it is possible to put on a number of sprays at stated inter- vals of from two to three weeks during the earlier part of the season and almost entirely miss the hatch from some peak of emergence of the moths. This was proved in 1929 when certain growers spraying by calendar date applied from five to seven sprays on late apples and suffered a high percentage of loss, while other growers in the same section kept their losses below 5 per cent with only four sprays properly timed by the bait traps. THE PRINCIPLE OF THE BAIT TRAP Control of the codling moth by spraying with arsenate of lead is primarily dependent upon having as perfect a coverage as possible at the time the young larvae or worms hatch from the eggs, so that they will be poisoned before entering the fruit. Naturally, with moths emerging over a long period (April to October), it is impossible to maintain a uniform coverage throughout the hatching period because of the rapid expansion of the leaf and fruit surfaces during t"he growing period and because of the weathering of the spray. The bait traps indicate that at certain periods, called peaks of emergence, there are many more moths in the field than at other times. Temperature, seasonal development, and various other factors may enter into this group emergence. These peaks of emergence are usually very pronounced, and, with suitable temperatures (60° Fahrenheit or above) at sunset, are followed by heavy egg deposition. It is, therefore, important that the spray applications be made after each of these peaks, with suitable evening temperatures ; for within 10 to 12 days these eggs hatch and the young worms enter the fruit. If the maximum coverage of arsenate is present during these peak hatch- ing periods, the greatest number of larvae will be destroyed. There may be a large number of moths in the field without heavy egg disposi- tion, for during periods of low temperatures at sunset there will be no moth activity. If the evening temperatures (say from an hour before sunset to an hour after sunset) are below 60° Fahrenheit very little if any moth flight will occur, and no eggs will be deposited. If, how- ever, this sunset period is sufficiently warm, egg laying will be in- creased. The maximum activity of the moths occurs during a period from 20 minutes before sunset to 20 minutes after sunset. It is important, therefore, not only to observe when these peaks of emer- gence occur but also to note whether the evening temperatures following these peaks are suitable for moth activity. 1932] Codling-Moth Bait Traps THE BAIT TRAP One type of bait trap consists of a pudding pan 9 or 10 inches across the top and about 3 1 /) inches deep. The color of the pan does not matter, but it must be enameled or of granite or glass, since the Fig. 2. — Codling-moth bait trap suspended in apple tree, Sebastopol, California. (Photograph by courtesy of E. O. Essig.) acid in the bait will attack tin and spoil the bait. Such pans may be purchased at most notion stores for 15 cents each. Three small holes are punched about equidistant in the rim of the pan. Through these holes wires are run to form the support or hanger (fig. 2). To the wire is attached a cord (No. 60 Seine twine preferred), which is 8 California Agricultural Extension Service [Cm. 63 carried up through a screw eye in a high limb at the top of the tree, and by which the pan is raised and lowered. A second screw eye at an angle and below the first will form a guide for the cord as it is returned to the ground and tied to a low limb. When no suitable limbs are found in the high tops, as often occurs in young pear trees or open-center trees, a standard may be erected by taking a pole or prop sufficiently long to reach from the ground to above the top of Fig. 3. — Bait trap suspended on a standard in a pear tree, San Jose, California. the tree and nailing a short cross-arm on the upper end. The screw eyes are set in the outer end of the cross-arm and a short distance down the pole. The pole is then tied to a main limb or the trunk of the tree and the cord run through the screw eyes, allowing the trap to be raised to the proper position (fig. 3). A newer type of trap which prevents the wind from splashing the contents may prove practical in some localities where high winds prevail. It consists of an inverted galvanized tin cone (coated on the inside with paraffin or Duco paint) about 18 inches deep and 6 inches in diameter at the top. A wire handle or bail forms the support at the top and a wire ring soldered into the bottom permits the string !9 32 ] Codling-Moth Bait Traps 9 from the screw eye in the limb to pass through it, and thus prevents the container from swinging in the wind and splashing. A 6-inch wire-screen sieve placed immediately below the surface of the bait prevents the insects from dropping into the narrow end of the cone, and serves as a means of removing the catch for counting. NUMBER AND DISTRIBUTION OF PANS In using the bait traps as indicators for timing spray operations in an orchard up to 40 acres, 8 or 10 pans are sufficient, though more may be employed. In larger orchards and in orchards with varying conditions such as elevation, exposure to wind, or nonadjacent blocks, it may be advisable to put in more than one series of pans. Late varieties of apples and pears usually show the highest moth catch and are best for trap trees. The pans need not be distributed over the entire area; it is sufficient to distribute them in a wide circle, two or three trees apart, to include a fair-sized representative block of the orchard. Pans should not be placed within six or eight rows of buildings, packing sheds, prop piles or driers, because the moths usually emerge earlier and in greater numbers near such structures than in the rest of the orchard. POSITION OF TRAP IN TREE Since the codling moths do most of their flying about the high tops or upper third of the trees, the traps should be hung as high as possible. Many more moths will be taken in pans hung high than those nearer the ground. The pan should also be in the open center or in an open section of the side of the tree where it is not sheltered by foliage, so that the moths can more readily gain access to the trap. The trap should be hung on the side of the tree away from prevailing wind, in order to prevent splashing of the bait. FORMULAS FOR BAIT A number of baits have been tried, including cider, vinegar, crushed apples, corn syrup, cane syrup, and malt, In the earlier work a 10 per cent dilution of vinegar was used, but the vinegar did not attract as well during warm weather. Molasses (10 per cent by 10 California Agricultural Extension Service l ClR - 63 volume) gave better results than most of the other combinations. In 1928 and 1929 the bait most successfully used was made with molasses as follows : Blackstrap molasses 1 pint Water 9 pints Yeast (compressed) 1 cake In 1929 a new product appeared which was superior to molasses in that it was always uniform in composition, fermented more readily, and was more efficient during periods of high temperature when the molasses bait thickened and often became inactive. The material is known a,s malt (Diamalt) and is of the consistency and appearance of a thick syrup. The formula is prepared as follows : Malt (Diamalt) 1 pint Water 19 pints Yeast (compressed) 1 cake Pour the required amount of Diamalt into the water and stir until dissolved. Dissolve the yeast cake in a small amount of water and add it to the Diamalt solution. Use at least a quart of the solution to a pan. In New Mexico these baits prepared without the addition of yeast but with the addition of a preservative (benzoate of soda, 0.2 per cent) are even more attractive. In a field test conducted at Sebastopol during the months of July, August, and September, 1931, in which Diamalt, corn syrup, and cane syrup were used with yeast and with benzoate, it was apparent that during periods of lower temperatures the Diamalt with yeast caught more moths but during higher temperature periods the cane syrup with benzoate caught the greater number. The average mean temperature of the coastal area is probably too low for the success of the benzoate formula, but it may prove more advantageous in the interior valleys. The average mean temperature during the test period was 60° Fahrenheit, and the total number of moths taken in 36 pans was 2,649. In making baits with yeast, since it takes several hours for the fermentation to start, it is best to prepare them in the morning and put them out in the pans in the sun. By evening the pans of bait will be attractive. Baits with benzoate are best prepared about two days in advance of use to permit natural fermentation to start. Do not prepare or allow the bait to stand in iron or tin receptacles. If it is necessary to keep the bait, put it in glass or enameled containers. 1932] Codling-Moth Bait Traps 11 Many chemical attrahents have been tried, alone and in combina- tion with the baits, by several investigators, but very few of them have shown an appreciable increase in the number of moths taken. It is apparent that the odor of the ester of the chemical must compare closely to that of the natural food to be effective. INSPECTION AND REFILLING OF PANS In California the pans should be put out the first week in April, and inspected and kept filled until the end of June, for information on the first brood of moths ; and from the last of June to the harvest time in September or October for the second brood. Through the periods when the moth is in active flight, daily inspections are re- quired. The total catch at each inspection should be tabulated as to date and number of moths taken. A semicircular piece of wire cloth cut smaller than the pan opening and used as a scoop is a convenient means of removing the insects from the surface of the liquid bait. The pans generally need refilling every fifth or seventh day accord- ing to the rate of the evaporation of the liquid. At refilling, the old syrup and dead yeast should be discarded and fresh material added. When the material in the pans is diluted by rain it should be discarded and the pans refilled. At least 1 quart of liquid is needed for each pan and often iy 2 quarts is better, on account of rapid evaporation. IDENTIFYING THE INSECTS CAUGHT Many kinds of insects are attracted to the pans, including the codling moth, skin worm moth, leaf roller moth, cutworm moths, wasps, several kinds of flies, and a few beetles. Most of these are injurious insects, but a few, such as the green lacewing, an occasional ladybird, and more rarely a honeybee, are beneficial insects. The important injurious insects may be determined by the following brief descriptions : Codling moth, Carpocapsa pomonella (Linn.) (fig. 4i): Adults are about % inch in length, bluish-gray with several very fine cross lines on the forepart of the front wings and a copper spot near the tip of each wing. This copper spot will help separate them from all other small gray moths. Common leaf roller, Archips argyrospila (Walker) (fig. 4 D) : Adults are about % inch long, fawn-colored to rusty brown with a light spot on the outer margin and several other spots irregular^ 12 California Agricultural Extension Service [Cir. 63 placed on the front wings. These usually are taken in great numbers through May and June. Pandemis leaf roller, Pandemis pyrusana (Kearfott.) (fig. 4 S) : Adults are usually % inch long, rusty-brown in color with darker diagonal cross band on each front wing. When at rest, the wings form a perfect bell shape. They are taken during summer and fall. B Fig. 4. — A, Codling moth, adult; B, pandemis leaf roller; C, apple skin worm; D, common leaf roller. All four insects are shown three times their natural size. (Photograph by courtesy of E. O. Essig.) Apple skin worm, Agyrotaenia franciscana (Walshm.) (fig. 4 C) : Adults similar to the common leaf roller, but smaller (% inch in length) and with darker markings, a dark diagonal band across the front wings, and a dark spot just above outer tip of each wing. They are taken from March to October. Cutworm moths: Large gray to brown moths, % to 1 inch in length, with large bodies. There are many species. They seldom feed on apples. 1932] Codling-Moth Bait Traps 13 CODLING-MOTH ROAD BULLETINS It is not necessary for every grower within a definite district to operate a series of pans; the catches will be fairly uniform unless there are definite factors, such as those mentioned earlier, that may vary the emergence. The practice of having the catch from a certain Fig. 5. — Bait-trap bulletin board used in Santa Cruz County, California. orchard or from several orchards throughout the district furnish the data for that particular section is sufficient. The data thus obtained may be placed each day on a bulletin board (3 by 5 feet or 4 by 6 feet) erected at a convenient centrally located place on the highway (fig. 5) and as the growers of the section pass, they may observe the records and determine the proper spray date. This plan has been successfully carried out in Sonoma County by the Farm Bureau and in Santa Cruz County by the Agricultural Commissioner's Office cooperating with the Farm Bureau. STATION PUBLICATIONS AVAILABLE FOR FEEE DISTRIBUTION BULLETINS No. No. .253. Irrigation and Soil Conditions in the 433. Sierra Nevada Foothills, California. 263. Size Grades for Ripe Olives. 279. Irrigation of Rice in California. 435. 283. The Olive Insects of California. 310. Plum Pollination. 331. Phylloxera-Resistant Stocks. 439. 343. Cheese Pests and Their Control. 348. Pruning Young Olive Trees. 349. A Study of Sidedraft and Tractor Hitches. 357. A Self -Mixing Dusting Machine for 440. Applying Dry Insecticides and Fun- gicides. 361. Preliminary Yield Tables for Second- 445. Growth Redwood. 364. Fungicidal Dusts for the Control of 446. Bunt. 447. 369. Comparison of Woods for Butter Boxes. 370. Factors Influencing: the Development 448. of Internal Browning of the Yellow Newtown Apple. 449. 371. The Relative Cost of Yarding Small and Large Timber. 450. 373. Pear Pollination. 374. A Survey of Orchard Practices in the Citrus Industry of Southern Cali- 452. fornia. 454. 379. Walnut Culture in California. 386. Pruning Bearing Deciduous Fruit 455. Trees. 389. Berseem or Egyptian Clover. 456. 392. Fruit Juice Concentrates. 393. Crop Sequences at Davis. 458. 394. I. Cereal Hay Production in California. II. Feeding Trials with Cereal Hays. 459. 395. Bark Diseases of Citrus Trees in Cali- fornia. 462. 396. The Mat Bean. Phaseolus Aconitifolius. 464. 404. The Dehydration of Prunes. 406. Stationarv Sprav Plants in California. 465. 407. Yield, Stand, and Volume Tables for 466. White Fir in the California Pine Region. 467. 408. Alternaria Rot of Lemons. 468. 409. The Digestibility of Certain Fruit By- products as Determined for Rumi- 469. nants. Part I. Dried Orange Pulp 470. and Raisin Pulp. 410. Factors Influencing the Quality of Fresh 471. Asparagus After It is Harvested. 416. Culture of the Oriental Persimmon in 472. California. 473. 417. Poultry Feeding: Principles and Prac- tice. 474. 418. A Study of Various Rations for Fin- ishing Range Calves as Baby Beeves. 419. Economic Aspects of the Cantaloupe 475. Industry. 476. 420. Rice and Rice By-Products as Feeds 477. for Fattening Swine. 421. Beef Cattle Feeding Trials, 1921-24. 479. 423. Apricots (Series on California Crops and Prices). 425. Apple Growing in California. 480. 426. Apple Pollination Studies in California. 427. The Value of Orange Pulp for Milk 481. Production. '428. The Relation of Maturity of California 482. Plums to Shipping and Dessert 483. Quality. 484. 431. Raisin By-Products and Bean Screen- ings as Feeds for Fattening Lambs. 485. 432. Some Economic Problems Involved in 487. the Pooling of Fruit. Power Requirements of Electrically Driven Dairy Manufacturing Equip- ment. The Problem of Securing Closer Rela- tionship between Agricultural Devel- opment and Irrigation Construction. The Digestibility of Certain Fruit By- Products as Determined for Rumi- nants. Part II. Dried Pineapple Pulp, Dried Lemon Pulp, and Dried Olive Pulp. The Feeding Value of Raisins and Dairy By-Products for Growing and Fattening Swine. Economic Aspects of the Apple In- dustry. The Asparagus Industry in California. A Method of Determining the Clean Weights of Individual Fleeces of Wool. Farmers' Purchase Agreement for Deep Well Pumps. Economic Aspects of the Watermelon Industry. Irrigation Investigations with Field Crops at Davis, and at Delhi, Cali- fornia, 1909-1925. Economic Aspects of the Pear Industry. Rice Experiments in Sacramento Val- ley, 1922-1927. Reclamation of the Fresno Type of Black-Alkali Soil. Yield, Stand and Volume Tables for Red Fir in California. Factors Influencing Percentage Calf Crop in Range Herds. Economic Aspects of the Fresh Plum Industry. Prune Supply and Price Situation. Drainage in the Sacramento Valley Rice Fields. Curly Top Symptoms of the Sugar Beet. The Continuous Can Washer for Dairy Plants. Oat Varieties in California. Sterilization of Dairy Utensils with Humidified Hot Air. The Solar Heater. Maturity Standards for Harvesting Bartlett Pears for Eastern Shipment. The Use of Sulfur Dioxide in Shipping Grapes. Adobe Construction. Economic Aspects of the Sheep In- dustry. Factors Affecting the Cost of Tractor Logging in the California Pine Region. Walnut Supply and Price Situation. Poultry Houses and Equipment. Improved Methods of Harvesting Grain Sorghum. I. Irrigation Experiments with Peaches in California. II. Canning Quality of Irrigated Peaches. The Use. Value, and Cost of Credit in Agriculture. Utilization of Wild Oat Hay for Fat- tening Yearline Steers. Substitutes for Wooden Breakpins. Utilization of Surplus Prunes. The Effects of Desiccating Winds on Citrus Trees. Drying Cut Fruits. Asparagus (Series on California Crops and Prices). BULLETINS— (Continued) No. 488. 489. 490. 491. 492. 493. 494. 495. 496. 497. 498. 499. 500. 501. 502. 503. 504. Cherries (Series on California Crops and Prices). Irrigation Water Requirement Studies of Citrus and Avocado Trees in San Diego County, California, 1926 and 1927. Olive Thinning and Other Means of Increasing Size of Olives. Yield, Stand, and Volume Tables for Douglas Fir in California. Berrv Thinning of Grapes. Fruit Markets in Eastern Asia. Infectious Bronchitis in Fowls. Milk Cooling on California Dairy Farms. Precooling of Fresh Fruits and Tem- peratures of Refrigerator Cars and Warehouse Rooms. A Study of the Shipment of Fresh Fruits and Vegetables to the Far East. Pickling Green Olives. Air Cleaners for Motor Vehicles. Dehydration of Grapes. Marketing California Apples. Wheat (Series on California Crops and Prices). St. Johnswort on Range Lands of California. Economic Problems of California Agri- culture. (A Report to the Governor of California.) No. 505. The Snowy Tree Cricket and Other Insects Injurious to Raspberries. 506. Fruit Spoilage Disease of Figs. 507. Cantaloupe Powdery Mildew in the Imperial Valley. 508. The Swelling of Canned Prunes. 509. The Biological Control of Mealybugs Attacking Citrus. 510. Olives (Series on California Crops and Prices). 511. Diseases of Grain and Their Control. 512. Barley (Series on California Crops and Prices). 513. An Economic Survey of the Los Angeles Milk Market. 514. Dairy Products (Series on California Crops and Prices). 515. The European Brown Snail in Cali- fornia. 516. Operations of the Poultry Producers of Southern California, Inc. 517. Nectar and Pollen Plants of California. 518. The Garden Centipede. 519. Pruning and Thinning Experiments with Grapes. 520. A Survey of Infectious Laryngotrache- itis of Fowls. 521. Alfalfa (Series on California Crops and Prices). CIRCULARS No. 115. Grafting Vinifera Vineyards. 178. The Packing of Apples in California. 212. Salvaging Rain-Damaged Prunes. 230. Testing Milk. Cream, and Skim Milk for Butterfat. 232. Harvesting and Handling California Cherries for Eastern Shipment. 239. Harvesting and Handling Apricots and Plums for Eastern Shipment. 240. Harvesting and Handling California Pears for Eastern Shipment. 241. Harvesting and Handling California Peaches for Eastern Shipment. 244. Central Wire Bracing for Fruit Trees. 245. Vine Pruning Systems. 248. Some Common Errors in Vine Pruning and Their Remedies. 249. Replacing Missing Vines. 253. Vineyard Plans. 257. The Small-Seeded Horse Bean (Vicia faba var. minor). 258., Thinning Deciduous Fruits. 259. Pear By-Products. 261. Sewing Grain Sacks. 262. Cabbage Production in California. 265. Plant Disease and Pest Control. 269. An Orchard Brush Burner. 270. A Farm Septic Tank. No. 279. The Preparation and Refining of Olive Oil in Southern Europe. 282. Prevention of Insect Attack on Stored Grain. 288. Phylloxera Resistant Vineyards. 290. The Tangier Pea. 292. Alkali Soils. 294. Propagation of Deciduous Fruits. 296. Control of the California Ground Squirrel. 301. Buckeye Poisoning of the Honey Bee. 304. Drainage on the Farm. 305. Limine: the Soil. 307. American Foulbrood and Its Control. 308. Cantaloupe Production in California. 310. The Operation of the Bacteriological Laboratory for Dairy Plants. 316. Electrical Statistics for California Farms. 317. Fertilizer Problems and Analysis of Soils in California. 318. Termites and Termite Damage. 319. Pasteurizing Milk for Calf Feeding. 320. Preservation of Fruits and Vegetables by Freezing Storage. 321. Treatment of Lime-induced Chlorosis with Iron Salts. 322. An Infectious Brain Disease of Horses and Mules (Encephalomyelitis). 13m-4,'32