February, '13] BISHOPP: STABLE FLY 121 



fed at the same time failed to deposit any eggs. Several of the flies, the 

 deposition of which is recorded in the table, fed one or more times 

 after the last deposition recorded but did not deposit subsequently. 



Experimental evidence indicates that fertilization does not take 

 place until after the flies have partaken of blood. Copulation has 

 been observed but a very few times. In the instances noted the act 

 took place some time after the flies had been fed, the duration of the 

 act being about five minutes. In one instance a fly deposited fertile 

 eggs without copulating with the male after the first deposition. 



Longevity of Adults. FHes kept in close confinement without 

 food or water die within two days. When water and sugar syrup 

 were supplied to flies in a cage about one foot square a single female, 

 of a lot of about fifteen males and females, survived for twenty-three 

 days. Individuals which were fed on blood at rather short intervals 

 lived seventeen days. It has also been noticed that when fruit or 

 moist straw is supplied the length of life of the flies frequently reaches 

 ten days. 



Duration of Stages. The length of the egg stage has been found 

 to vary from one to four days. Temperature and humidity, as well 

 as the length of time eggs are retained by the female, appear to mark- 

 edly affect the rapidity of incubation. The larval period has been 

 found to vary from about eleven to over thirtj^ days. Records made 

 during cold weather would doubtless show this stage to be much 

 longer. The suitability of food also decidedly affects development. 

 As is shown in the accompanying table the minimum developmental 

 period from egg to adult ranged from twenty-three to thirty-two days, 

 according to the character of the food supplied. The pupal stage 

 varies from six to about twenty days and the total period from egg 

 to adult from nineteen to over forty-two days. 



It has been found that abundance of food hastens development 

 considerably. This is brought about in two ways, namely, by enabling 

 the larvae to choose suitable portions of the food, and where there is a 

 large amount of straw or other food material in a pile the heat gener- 

 ated stimulates development. Even during the late fall in north 

 Texas, when the minimum temperature reached thirty degrees, fre- 

 quently the straw where larvae were found to be developing was very 

 warm. In larger stacks this heat may persist through the winter. 



Hibernation. No notes have been made on hibernation but 

 examinations of stacks in the middle of December show an abundance 

 of larvae in various stages of growth and many pupae. Adults have 

 also been found active and feeding on animals on December 18. It 

 is thought that adults may be more or less active in southern latitudes 

 during warm periods throughout the greater part of the winter, and 



