February, '13] BISHOPP: STABLE FLY 119 



freely from one animal to another many times before becoming replete, 

 thus giving an opportunity to convey disease mechanically. 



On account of the probable relation of this insect to the transmission 

 of a number of diseases, the study of its feeding habits in relation to 

 climatic conditions is important. It has been found that adults will 

 feed in midday during extremely hot weather and also when the tem- 

 perature is as low as 55 degrees Fahrenheit. The minimum feeding 

 temperature may be even lower than this. During rainy weather the 

 flies are largely driven into sheltered places. This accounts for the 

 presence of adults which has been observed heretofore in the habita- 

 tions of man at such times. The flies have not been observed to be 

 more persistent in their feeding during cloudy weather than in clear 

 weather although they continue to attack hosts during showers or cool, 

 drizzling rains. The fly may also bite by artificial light when free in 

 a room. 



Reproduction. In a large series of tests flies have been found 

 never to deposit before the third feeding on blood and usually four 

 engorgements are necessary. There is no indication that reproduction 

 ever takes place unless blood is engorged, however it is a common 

 habit of flies to partake of other liquid food. During deposition they 

 frequently feed upon the moisture on rotten straw and also have been 

 observed to take up moisture from manure as well as to drink freely 

 from plain or sweetened water when it is supplied to them in con- 

 finement. 



After the third or fourth feed, when the blood has been digested, 

 the flies seek suitable places for depositing their eggs. Deposition 

 has been observed both in confinement and in the field. Upon opening 

 a straw stack which had become drj^ on the surface, thus exposing the 

 rotting portions beneath, the flies immediately assembled and some- 

 times crawled down into the straw to a depth of several inches and 

 began laying eggs. These may be laid singly or in bunches of as many 

 as twenty-five or thirty. The ovipositor is greatly extended and used 

 as a tactile organ in order to find a crevice in which to place the eggs. 

 During active depositon from seven to nine eggs are deposited per 

 minute and the entire mass is usually deposited in less than half an 

 hour. Immediately after depositing the females are ready to feed 

 again and this feeding is usually followed within a dsij by another 

 deposition. The greatest number of depositions observed by a single 

 fly was three, a total of 278 eggs being deposited. Frequently two 

 feedings are necessary after a given deposition before another lot of 

 eggs is laid. As the temperature becomes lower greater numbers of 

 feedings are required to produce the same number of depositions. In 

 one instance a female was engorged more or less completely fourteen 



