Februan-, '15] BISHOPP-DOVE-PARMAN: HOUSE FLY BIOLOGY 



65 



is known regarding longevity in the United States, particularly in the 

 Southern States. In England, Doctor Hewitt found it possible to 

 keep house flies alive for seven weeks in the summer time. Doctor 

 Griffith, in his experiments, also in England, had a fly live for sixteen 

 weeks. 



We have conducted a large number of experiments in Dallas under 

 v^arying conditions of climate, food, and cages. Representative experi- 

 ments are cited in Table No. 3. It will be observed that the longevity 

 is greatly reduced where food is not given; the usual longevity being 

 from two to three days when no food or water was supplied, while 

 with food supplied it ranged from a very few days up to fifty-three days. 

 This maxim^um record was mxade during late fall and early winter. 

 Food and breeding ijiaterial were supplied and eggs were deposited by 

 flies in this test. In a few tests horse manure alone was supplied. 

 This prolonged life slightly but did not seem to form a maintenance 

 ration, and no eggs were deposited by flies under such conditions. 

 During summer the usual longevity of flies, in cages at Dallas, supplied 

 with an abundance of food and breeding m.aterial, was from two to 

 four weeks. Cool weather invariably prolongs the life of the adults, 

 correspondingly delaying reproduction, as has been stated. 



Hibernation 



It has been assumed generally until recently that the house fly 

 passes the winter in the adult stage only. No definite experiments 

 have been reported to substantiate this belief, although a considerable 

 amount of circumstantial evidence ^has been presented by various 

 authors; such as the observations by Doctor Hewitt, that flies dissected 

 in fall had much fat stored up in their bodies and in spring this fat 

 was not in evidence.^ The finding of adults in dormant, semi-dormant 

 and active states in various situations in mid-winter, and the greater 

 longevity exhibited by adults emerging late in fall, has also lent weight 

 to this conclusion. It is our opinion that these conditions do not 

 necessarily indicate that this species passes the winter in the adult 

 stage. 



Our experiments, as will be shown later, prove that the house fly 

 can pass the winter in the immature stages in the vicinity of Dallas 

 and Uvalde. Moreover, in our tests we failed to get adults to live 

 through the winter. All our observations indicate that flies which 

 are not kept cold enough to become inactive will either deposit, if the 

 temperature is sufficiently high, or die comparatively soon. It is 

 conceivable that some adult flies may happen to find shelter, which 



1 1910. Hewitt, C. G. The house fly; a study of its structure, development, 

 bionomics and economy, p. 364. 

 6 



