88 



DIPTERA OF MINNESOTA. 



The larvje, also carnivorous, occur in rotten wood and other veg- 

 etable matter, such as decomposing leaves and in the soil. Eggs are 

 laid in the soil or in rotting trees, the latter place doubtless being 

 chosen because such a locality abounds in the larvae of other insects. 

 Aldrich (1905) lists 552 species in North America alone, a very few 

 of them being of doubtful authenticity, while WilHston and Sharp 

 state that there are something like 3,000 described species of Robber 

 Flies in the world. 



These insects may be 

 seen upon the ground or 

 upon the foliage of trees. 

 When disturbed in the for- 

 mer position they rise 

 quickly, making a sharp 

 buzzing sound, and light 

 again a short distance be- 

 yond. The members of 

 this family unite in having 

 a firm, horny proboscis, 

 adapted for piercing their 

 victims, either pointing for- 

 ward or directed down- 

 ward. 



Fig. 81. Promaclius vcrtchratus. Original. 



MYDAIDAE, 



Mydas-FUes. 



Large flies, the largest of the North American Diptera, resembling 

 the Robber Flies superficially. The adults, like those of the preced- 

 ing family, are predaceous. The larvae live in decaying wood, and 

 some, like the larvae of the Asilids, prey upon the larvae of beetles. 

 About 100 species are known, many of which occur in Australia and 

 Africa. Mydas clavatus, Drury, a striking species (see Fig. 15, Col- 

 ored Plate II), has been taken in Minnesota. The colored drawing 

 represents the natural size of the fly. 



