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Show HOW DOES THE HOUSE FLY j l'ASS THE WINTER MONTHS j : ! Where does the annual crop of flies come from, is a question frequently fre-quently asked of the bureau of entomology, ento-mology, of the United States department, depart-ment, of agriculture. The prevailing opinion that the house fly lives through the winter as an adult, hiding hid-ing in cracks and crevices of buildings, build-ings, appears to be erroneous. Under outdoor conditions house flies ar killed during the first really cold nights that is, when the temperature tempera-ture falls to about 15 degrees or 10 degrees F. In rooms and similar places protected from winds and par-lially par-lially heated during the winter flies have been kept alive in cages for long periods; but they never lived through the entire winter. There is no reliable evidence whatever that adult house flies emerging during October and November pass the win-ler win-ler and are able to deposit their eggs the following spring, although they may continue active in heated buildings build-ings until nearly the end of January. On the other hand, there is evidence that house flies pass the winter as larvae and pupae, and that they sometimes breed continuously throughout the winter. In experiments experi-ments at both Dallas, Tex., and Beth-esda, Beth-esda, Md., house flies have been found emerging during April from heavily infested manure heaps which had been set out and covered with cages during the preceding autumn. In the Southern states, during warm periods in midwinter, house flies may emerge and become somewhat troublesome; they frequently lay eggs on warm days. The second way in which the housa fly may pass the winter is by continuous contin-uous breeding. House flies congregate congre-gate in heated rooms with approach of the winter season. If no food or breeding materials are present they eventually die. However, where they have access to both food and suitable substances for egg laying they will continue breeding just as they do out doors during the summer. Even In very cold climates there are undoubtedly undoubt-edly many places, especially in cities, where house flies would have opportunity oppor-tunity to pass the winter in Hiis manner. |