2 78 



ECONOMIC ENTOMOLOGY 



spinach as a trap crop; plow deep and harrow as soon as crop is 

 removed. 



Lesser House-fly {Homalomyia canicularis Linn.). — This fly is 

 smaller than Musca domestica, and may be observed in houses in early 

 summer. As an Anthomyiid it can be readily distinguished from the 

 true muscids by the venation of the wings. In this species the middle 

 tibiae are without a tubercle. 



The larva, )^5 inch long, is markedly different from that of Musca. 

 It has a flattened body with a double row of spiny processes. It 

 lives in waste vegetables and animal matter, and no doubt is responsible 



Fig. i8o. — The little house-fly {Homalomyia brevis). Female at left; male next, 

 with enlarged antenna; larva at right. All enlarged. {After Howard.) 



for the transmission of certain diseases. It becomes full grown in 

 about a week, sometimes prolonged to 3 or 4 weeks. 



The Little House Fly {Homalomyia brevis Rond.) occurs about 

 outbuildings and breeds in human excrement. It acts, no doubt, 

 as a disease carrier (Fig. 180). 



The Latrine Fly {Homalomyia scalaris Fab.) is also under suspicion 

 as a carrier of contagion. Middle tibia with a tubercle. 



TACHINIDiE (TACHINA FLIES) 



These flies are useful in that the larvag or maggots are parasitic 

 within the bodies of injurious caterpillars. The female tachina fly lays 

 her eggs upon the caterpillar or upon the leaves of the food plant, 

 and the maggots on hatching bore their way through the walls and 



