UNIVERSITY OF CALIFORNIA 
 
 COLLEGE OF AGRICULTURE 
 
 BERKELEY 
 
 Agricultural Experiment Station 
 
 BENJ. IDE WHEELER, President 
 THOMAS FORSYTH HUNT, DEAN AND DIRECTOR 
 H. E. VAN NORMAN, VlCE-Dl R ECTOR AND DEAN 
 University Farm School 
 
 CIRCULAR No. 127 
 March, 1915 
 
 HOUSE FUMIGATION 
 
 BY 
 C. W. WOODWORTH 
 
 California is remarkably free from the otherwise ubiquitous bedbug 
 and when it does make its appearance in a house it therefore causes 
 great alarm. It is most frequent perhaps in bunk houses and is one 
 of the problems of everyone employing' migratory laborers. Very 
 rarely in this country the insect is found in poultry houses. 
 
 Proboscis 
 
 Prdthorax 
 
 Scutellum 
 Elytron 
 
 Micrograph of common bedbug, crushed in mounting to show the 
 mouth parts and the segments of abdomen, and sketch with these joints 
 in normal position and the names of structures used to distinguish 
 species of bedbug.* 
 
 * The only household species in California is the common bedbug of Europe, 
 Cimex lectularius Linneaus, probably introduced into this country with the 
 earliest settlers. Another bedbug, Cimex hemipterus Fabricus, is a tropical 
 American species without the conspicuous broad flattened edges on the pro- 
 notum. Two South American species were described fifty and sixty years ago — 
 Cimex foedus Stal, similar to C. hemipterus and Cimex valdivianus Philippi close 
 to C. lectularius. Since the beginning of this century three other American 
 species have been discovered: Haematosiphon inodorus Duges, infesting poultry 
 in Texas, New Mexico and southward, having a proboscis long enough to reach 
 back to the base of the hind legs; Cimex pilosellus Howarth on bats here in 
 California and elsewhere in North America with the inner edges of the elytra 
 longer than the scutellum, and Oeciacus vicarius Howarth in nests of swallows 
 from California and elsewhere, which has the body clothed with long silky hair. 
 
The most satisfactory treatment for bedbugs is fumigation with 
 cyanide. This method has been practiced many years in California, 
 particularly in the southern part of the State, where there are many 
 people familiar with the treatment of orchard trees with the gas. There 
 is no reason why the method should not be used everywhere, whenever 
 the bugs appear since the method is simple and easy to apply. 
 
 MATERIALS FOR FUMIGATION 
 
 Cyanide, the source of the hydrocyanic-acid gas, should be pur- 
 chased in the egg form, the same as is now used in orchard fumigation. 
 This is a pure sodium cyanide and each egg weighs approximately one 
 ounce. It is possible to obtain good results with other forms of this 
 cyanide but the egg form is most convenient. The least desirable 
 form is powdered cyanide, because of the violent production of the 
 gas causing spattering of the acid about the room. 
 
 Acid is necessary to set free the gas from the cyanide. Sulphuric 
 acid is the cheapest acid and the one universally used — it is the prac- 
 tice to use more than is really necessary because it is so cheap. The 
 ordinary strong acid is the proper material to buy. By weight use 
 about twice as much acid as of the cyanide. It will be easier to measure 
 out the acid by volume in which case one and one-quarter parts are 
 about equivalent to two parts by weight. 
 
 Water is necessary for the proper generation of the gas, so that the 
 residue sodium or potassium sulphate will remain in solution and not 
 crystallize. The amount to use varies with the character of the cyanide. 
 If the eggs are used, twice as much water as cyanide is necessary, and 
 if lower grade material is employed, use three times as much water. 
 
 The recommendation made above is as follows. 
 
 By weight By volume 
 
 Cyanide (eggs) 1 part 
 
 Sulphuric acid 2 parts l x /4 parts 
 
 Water 2 parts 2 parts 
 
 THE AMOUNT TO USE 
 
 Measure the room to be fumigated, calculate the cubic contents and 
 divide the number of cubic feet by the grade of cyanide used. Thus 
 if the room were 12 X 15 X 10 the cubic contents would be 1800, and 
 if one could only obtain 30 per cent potassium cyanide, 60 ounces would 
 be necessary. If 98 per cent potassium cyanide were available, 18 
 ounces would be enough and with the eggs, which are equivalent to 
 
128 per cent and are generally so labeled, 14 ounces would be about 
 right. In other words, when the cyanide eggs are used as recommended 
 use one-quarter less ounces than the number of hundreds of cubic 
 feet in the room. 
 
 This is on the assumption that the room is tight or made so. When 
 the construction is such that the room cannot be made tight good 
 results may still often be secured by making the dose much stronger. 
 No rule can be given for dosage under these conditions and the fumi- 
 gator will have to use his best judgment and then take chances. 
 
 HOW TO MAKE THE ROOM TIGHT 
 
 In most cases it will pay to go to some trouble to close the cracks 
 about windows, chimney holes, etc. This can be done by pasting paper 
 over them. Simply stuffing paper into them is better than nothing. 
 Professor Herriek, of Cornell University, has used paper simply wetted 
 with water instead of paste and found it would stay in place long 
 enough for the treatment. A great deal of the fumigation in this 
 state has been done without trying to make the room tighter than it 
 was built, arguing that it was cheaper to use more chemicals than to 
 spend the time making the room tight. This will have to remain a 
 question for the judgment of the fumigator. As remarked above, 
 rules as to dose can onlv be given on the basis of a tight room. 
 
 APPARATUS FOR FUMIGATING 
 
 Where orchard fumigation is practiced and regular generators 
 are available they are perhaps the most satisfactory. However, any 
 tight wood or earthenware vessel of proper size will do. We have 
 used the ordinary wooden water bucket and the common bedroom bowl 
 and pitcher, also crocks and jars. It is better to have several generators 
 when the room is large, putting not over a pound of cyanide in each. 
 Spattering of the acid out of the generator is less liable to occur when 
 the amount generated is small. We have followed the practice of 
 spreading out several layers of newspaper upon which the generator 
 is set to make sure not to spatter the floor. A paper sack to hold the 
 cyanide for each generator is recommended to give ample time to 
 get out of the room before the production of the gas begins, since the 
 acid requires some time to soak through the paper and attack the 
 cvanide. 
 
TIME OF TREATMENT 
 
 The practice in orchard fumigation is to leave the tents on the trees 
 fifty minutes or an hour, and at least this length of time should be 
 allowed in house fumigation. Our practice has been three or four 
 hours. For instance, if a house is vacated from ten to three o'clock 
 the fumigation could take four hours, leaving an hour for ventilation, 
 which is ample. In empty houses the commoner practice is to fumigate 
 in the afternoon and leave them closed until the following- morning. 
 
 DISPOSAL OF REFUSE 
 
 The residue from fumigation generators is sodium or potassium 
 sulphate dissolved in a liquid which contains an excess of sulphuric 
 acid and more or less hydrocyanic acid. This may be disposed of by 
 digging a small hole in the ground into which the generators are 
 emptied and the hole then filled up with soil. The material will tem- 
 porarily injure the soil, but not permanently. 
 
 The vessels need only be washed out with water. Sometimes in a 
 wooden or porous earthenware vessel an effervescence may appear some 
 days later. This is the sulphate and is perfectly harmless. 
 
 PRECAUTIONS 
 
 The most important precaution is to avoid breathing the strong 
 gas as it comes from the generator. Strong cyanide gas is instantly 
 fatal and breathing it would be equivalent to looking down the muzzle 
 of a gun to see the bullet start. If this one fact is kept clearly in mind 
 fumigation is not more risky than handling firearms. 
 
 After fumigation is over it is quite safe to enter a room and open 
 the windows, but it is wise not to breathe the air any more than 
 necessary in doing so. 
 
 When fumigation is being done it is well to vacate the whole house 
 so as not to take any chances. 
 
 Cyanide gas does not injure any fabric nor metal, but would kill 
 plants at the strength used for house fumigation, and all moist food 
 should be removed because the gas is absorbed by water.