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Bisiiori' (F, C). The Stable Fly {Stomoj-ijs calcitrant, I.)» an 

 important live-stock pest. — Jl. Ecun. Entum., vi, uo. 1, Feb. 

 1913, pp. 112-126, 3 plates. 



A very severe outbreak of stable fly occurred iu North Texas 

 during August 1912, the flies breeding in large numbers in straw 

 stacks. The great abundance of the fly was practically co-exten- 

 sive with the great grain growing area. 



Injury to live stock was brought about in a number of ways. 

 Probably " Avorry " due to the attacks of great numbers of the 

 flies was the most serious. Loss of blood was also by no means 

 a small matter, as it was estimated that as many as a thousand 

 flies might be present on a single animal at one time, so that the 

 blood supply of the animals was heavily drawn upon. Many 

 deaths Avere due to the fact that the weakening of the cattle 

 induced acute Texas fever in those which already harboured the 

 disease organism in their blood. The lessening of the milk supply 

 in all milch cows throughout the affected area was an important 

 source of loss, the milk output in some cases being reduced from 

 40-60 per cent. Loss of flesh iu all animals iu the fly zone was 

 very noticeable. The stamping of horses often caused lameness, 

 whilst swollen and stiff joints were commonly produced by 

 animals standing too long in water to escape the flies. 



At the same time the flies were especially numerous in other 

 parts of the United States, notably in South Dakota and Georgia, 

 also in Kansas, Nebraska and Southern Louisiana. 



The stable fly breeds in the straAv of various cereals and in 

 manure. Examinations of accumulations of weeds failed to show 

 the presence of Stomoxys larvae. Far more larvae appear to 

 develop in oat straw than in that of wheat. Most of the flies 

 breed in -the lower portions of the stacks, although a few pupae 

 were found on the top of a stack 15 feet high. After the larvae 

 develop they show a tendency to work dowuAvards or at least to 

 follow the moisture as the surface of the stack dries. Pupation 

 occurs anywhere in the straw, a favoured position being between 

 the straw and the surface of the ground. It has been found that 

 adults will feed in midday during very hot weather and also when 

 the temperature is as low as 55° F. During rainy weather the 

 flies are largely driven into sheltered places. In a large series of 

 tests flies have been found never to oviposit 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, and it is a common habit of these flies to 

 partake of other liquid food. The eggs are laid preferably on 

 rotting straw, singly or in bunches of 25 or 30. Oviposition 

 usually takes about "half an hour. Immediately after ovipositing 

 the females are ready to feed again and this feeding is usually 

 folloAved within a day by another deposition. The greatest 

 number of ovipositions observed for a single fly was three, a total 

 of 278 eggs being deposited. Experimental evidence indicates 

 that fertiirsation does not take place till the flies have partaken 



of blood. 



Unfed flies only lived fur two days; wlien supplied_ with Avater 

 iiud suo-ar syrup one survived for 23 days ; Avhilst individuals fed 



