266 



AMERICAN BEE JOURNAL 



July 



CONTROL OF THE WAXMOTH 



Notes on Fumigation of Combs to Prevent Destruction 

 When Not in the Care of the Bees 



By G. H. Cale 



Beemoths are most effective de- 

 stroyers of honeycomb, and it re- 

 quires care to protect combs, which 

 are not in use, from injury. It is in- 

 teresting to note that the larvse of the 

 moths prefer to feed on pollen and 

 on the cast skins and debris left in 

 the cells of the brood-combs, a habit 

 which directs them to the most valua- 

 ble part of the colony equipment. 



Paddock shows (Bulletin 128, 

 Texas Agricultural Experiment Sta- 

 tion, "The Beemoth or Wax Worm") 

 that temperature greatly influences 

 the life history of the larger beemoth 

 (Galleria meilonella) , and the great- 

 est number of generations occur in 

 the South, where the summers are 

 longer and the mercury stays higher 

 on the scale. At least three broods 

 develop annually at College Station, 

 Texas. Some beekeepers in the 

 South report large losses of colonies, 

 due to moth injury, but much of this 

 loss may come after the colonies are 

 weakened from other causes. Where 

 conditions are so favorable for devel- 

 opment, greater watchfulness is ob- 

 viously necessary. In the North, the 

 average life history is longer and at 

 best there are probably seldom more 

 than two generations a summer, al- 

 though when the summers are espe- 

 cially long and hot, the chance of 

 added generations increases. 

 Natural Enemies 



The most effective natural enemy 

 of the beemoth is the honeybee itself. 

 It is an axiom that strong colonies of 

 bees will rarely tolerate the presence 

 of moths, but when the bees are not 

 sufficiently numerous to care for all 

 the combs the moths may then infest 

 unoccupied areas. Some races of 

 bees, however, show less of a dispo- 

 sition to rid the hives of intruders 

 than others. It is characteristic of 

 good Italians to clean house thor- 

 oughly, and the use of strong colo- 

 nies of Italian bees is now considered 

 a necessity in the control of European 

 foulbrood. Their value is still further 

 emphasized in the control of the bee- 

 moth, since there is no better insur- 

 ance against the loss of combs from 

 moths than to leave them as long as 

 possible in the care of such colonies. 



Moths and moth larvae are both 

 quickly killed by freezing tempei-a- 

 tures, and in the fall, in the North, 

 when the temperature becomes low 

 enough, there is no further danger of 

 moth injury. It is usually sufficient 

 to stack the supers or hives of combs 

 away, tightly covered, until again 

 needed, but where zero temperatures 

 do not occur, some of the moth eggs, 

 at least, will probably live over winter 

 to hatch in the spring. In the South, 

 although the temperatures may be 

 sufficiently low to kill the moths if 

 they are exposed in different stages 

 of their life history, the more pro- 



tected ones will escape and remain as 

 a constant source of injury. 

 Carbon Bisulphide 



The most effective control for 

 moths, when combs are not in use and 

 the temperature is favorable for de- 

 velopment, is the ordinary practice of 

 fumigation. The usual carbon bi- 

 sulphide, or "high life," is efficient in 

 its action, and readily obtained. It 

 is purchased as a liquid, but when ex- 

 posed to the air it volatilizes rapidly 

 as a gas, about two and one-half times 

 heavier than air, which settles rapidly 

 to the lowest possible level. This gas 

 is dangerously inflammable when 

 mixed with air, and often explosive. 

 It is not poisonous, as frequently sup- 

 posed, but kills by suffocation, and 

 honey with which it comes in contact 

 is perfectly safe to use. The action 

 of the gas is most effective when the 

 temperature is sufficiently high to al- 

 low rapid evaporation of the liquid 

 and it is therefore obviously most ef- 

 fective in warm weather, which is 

 also the time when moths are the 

 most active. 



Combs to be treated may be left in 

 hives or supers and the latter piled in 

 stacks. To prevent the escape of gas, 

 the bottom body should be set in an 

 inverted hive cover on a newspaper 

 so arranged that a tight joint is made. 

 The edges of the hives should be 

 scraped to remove propolis and other 

 adhering materials, and the remain- 

 ing spaces due to unevenness may be 

 closed easily with refuse wax, or with 

 mud. A measured amount of carbon 

 bisulphide is poured in a dish set on 

 the frames of the top hive. A large, 

 flat dish is preferable, since it exposes 

 a considerable amount of the liquid to 



Carbon bisuliiliitlc is placed in a shallow pan 

 in an empty super above the combs. 



evaporation. An empty hive or su- 

 per, set about the fumigant and cov- 

 ered tightly, completes the operation. 

 If care is used, the gas may be con- 

 fined for a long time. 



Paddock found that the moths were 

 killed by carbon bisulphide in 15 to 

 20 minutes, but that pupae and pro- 

 tected larvse required a period of 

 some length. With the dosage he 

 used the eggs were not killed. Heavy 

 doses will probably kill the eggs, but 

 it is not generally considered practi- 

 cal or economical to use large 

 amounts of the fumigant. The usual 

 incubation period of the egg is 7 to 

 9 Vz days, and the newly hatched lar- 

 va do little damage until they reach 

 the midribs of the combs, which re- 

 quires a minimum of about four days. 

 A second examination at the end of 

 ten days or two weeks, therefore, will 

 show what combs need a second dose. 

 A third fumigation is not necessary 

 as long as the stacks remain tight. 

 Amounts to Use 



The following are approximately 

 the amounts of the bisulphide recom- 

 mended by Paddock: 



For 10-frame Langstroth hives — 1 

 ounce to each 3 hive-bodies. 



For 10-frame shallow supei-s — 1 

 ounce for 5 supers and one-quarter 

 ounce additional for each super there- 

 after. 



For large hives, such as the Dadant 

 or Jumbo, one-half ounce is sufficient 

 for each hive-body. Where 6-inch ex- 

 tracting supers are used, two supers 

 are equivalent to one large hive. 

 Since these amounts supply gas suf- 

 ficient for the space inside the stack, 

 the empty protecting hive-body or 

 super on top is included in the count. 

 Sulphur 



Sulphur, or flowers of sulphur, is 

 sometimes used as a fumigant, but it 

 is not as effective as the bisulphide. 

 In this case the material comes in 

 lumps, or as a powder, which is 

 burned, forming a suffocating gas, 

 sulphur dioxide. The sulphur must 

 be burned at a high temperature to be 

 most effective, and the better pro- 

 tected forms of the moth requires ex- 

 posure to large amounts of the ga^ 

 for a considerable time before death 

 occurs. The gas is most effective in 

 the first five or six hours, and the 

 fumigation is practically complete in 

 ten to twelve hours. The eggs are 

 not affected. 



Since the gas is considerably 

 lighter than air, it rises as far as pos- 

 sible, and the sulphur must therefore 

 be placed beneath the combs which 

 are to be fumigated. The stacks 

 should be as tight as for the bisul- 

 phide treatment and the dish contain- 

 ing the sulphur may be set in an 

 empty body at the bottom. The sul- 

 phur may be burned by putting it in 

 a dish that is not held together with 

 sold.ir and setting the dish on a brick 

 or a pan of cold ashes to prevent 

 burning the floor. Sulphur is cheaper 

 than bisulphide, and it is not neces- 

 sary to economize in its use. In fact 

 better results are obtained by using 

 excessive doses. Sanitary entomolo- 

 gists have a standard of 4 pounds to 

 1,000 cubic feet, where the enclosure 

 is not air tight. Figuring this down 



