February, '15] BISHOPP-DOVE-PARAIAN: HOUSE FLY BIOLOGY 



59 



5.30 p. m. and August 21, 10.30 a. m. and were supplied with milk, 

 peaches, and horse manure. The temperature and humidity in these 

 two cases were practically identical, yet the flies on peaches required 

 sixteen days for egg production while those given the variety of foods 

 deposited in five days. 



The humiditj^ also appears to have a bearing on the duration of this 

 period. In general when the temperatures are high or moderately 

 high, increased humidity seems to hasten egg la>dng. This is probably 

 partially due to the effect of humiditj^ on the food and breeding sub- 

 stances — keeping them moist and thus attractive. Our observations 

 lead us to think that sunshine, aside from higher temperature, has a 

 stimulating effect on reproduction and other activities in flies. 



The preoviposition periods recorded in the table are the shortest 

 observed in each lot of flies; in many cases only a few masses of eggs 

 were deposited in a test. In several tests, with large numbers of flies 

 under favorable conditions, a number of females began depositing 

 about the same time, or not more than twenty-four hours later than 

 the first. 



In most of our tests with single pairs the preoviposition periods were 

 longer than when a number of flies were kept together. 



At Uvalde several preoviposition experiments were conducted but 

 in nearly all the flies failed to deposit. In one test made in June the 

 period was about six days. 



Milk appears to be a good food for ova development. This sub- 

 stance ^dth manure was found to be adequate for producing oviposi- 

 tion. Over-ripe fruit with manure was also found to be satisfactory. 

 The effect of the condition of food on egg production may be illustrated 

 by referring to Table No. 1. In one instance where railk and horse 

 manure were supplied deposition took place in six days. In a parallel 

 test where partially ripened peaches were substituted for the milk, the 

 &st deposition occurred on the twentieth day after emergence. 

 Manure either of horses or cattle, appears to be inadequate as a food 

 for egg production in the house fly. 



Based upon our experiments it appears that, in Texas, it is necessary 

 to capture or destroy the female flies within four days after emergence 

 in summer and within ten days in fall and early spring in order to 

 prevent reproduction. The shortness of the preoviposition period as 

 determined by us emphasizes the importance of laying special stress 

 on the prevention of breeding by caring for breeding media, as urged 

 by Doctor Howard, rather than the destruction of adults, as the more 

 important control measure. This seems especially true in the tropics 

 and subtropics where the preoviposition period is short, successive 

 depositions frequent and longevity of the adult reduced. 



