THE FLIES 39 



swept up and burned. The use of poisonous liquids set around in dishes 

 has but little efficacy and for other reasons is not to be recommended. 

 Sticky fly paper, to be most effectual, should be placed in parts of the 

 room where there is most sunlight, as in the vicinity of windows. 



In this connection it should be borne in mind that adult house flies 

 and their allies seek the light, while their larvae avoid it, characteristics 

 referred to in the first case as light positive and in the second as light 

 negative. This habit as to light is to be reckoned with and taken ad- 

 vantage of in measures looking to fly control. 



Stomoxys Calcitrans 



Stromoxys stabulans. Stable fly; stinging fly. Muscidse (p. 37). 

 About the size of the house fly. The color is brownish gray; proboscis 

 black, slender, bent near its base, and extending forward from the head, 

 fitted for piercing. The thorax bears four longi- 

 tudinal stripes which may be more or less broken. 

 The abdomen is stout, grayish, and spotted dor- 

 sally. The wings hyaline, and when at rest widely 

 spread apart at the tips. The fly rests with its 

 head well elevated and with wings sloping later- 

 ally downward and outward (Fig. 22). 



The eggs are about one mm. in length, curved 



^?, , , -x ■ T f ■ 1 X T Fig. 22.— Stomoxys cal- 



on one side, on the opposite side straight and citrans, enlarged. 

 grooved. The larvae resemble those of the house 



fly. They may be differentiated by the posterior stigmal plates, 

 which in the larvae of the house fly are large, irregularly oval, and close 

 together, while in Stomoxys they are smaller, round or triangular, and 

 much farther apart. 



Life History. — The life-cycle of the stable fly is considerably longer 

 than that of the house fly; like the latter it breeds in horse manure, but 

 not to the same extent. Manure well mixed with straw is that most 

 sought. Ideal for the deposition of its eggs are damp and fermenting 

 collections of such material as cut grass, alfalfa, hay, grain, or piles of 

 weeds. The eggs are deposited deep into the fermenting mass, and, 

 under favorable conditions of temperature, will incubate in about three 

 days. The larvae are active feeders and complete their growth in from 

 twelve to thirty days. As in related flies, the puparium is formed by 

 the hardening of the last larval skin. The duration of the pupal stage 

 will again vary according to weather, lasting from six to twenty days, or, 

 if cool, it may be much longer. About twelve days may be taken as an 

 average period. The time required for complete development may 

 accordingly be set down as from twenty-five to thirty days under 

 ordinarily favorable conditions. It is probable that the species is car- 

 ried over the winter months in our Northern States in the larval and 



