FIELD BOOK OF INSECTS. 



MYDAID^E 



This is a small family of large flies which resemble the 

 thin-bodied Asilidae and have similar habits but whose 

 probosces have fleshy lips at their tips. Only one genus, 

 Mydas (Plate LXVII), occurs in the Northeast. 



ASILIO.E 



In Plate LXVII, Leptogaster, Dasyllis, Erax, and Asilus 

 of the large family of Robber Flies are illustrated, the two 

 last-named being the more typical. Some species are two 

 inches long ; they are frequently seen swooping upon insect 

 victims in mid-air or snatching them off of leaves and 

 carrying them away to a convenient spot where the sucking 

 of vital fluids may be quietly completed. The hairier and 

 stouter type is just as predaceous and possibly their 

 resemblance to peaceful bumble-bees helps them to get 

 close to their prey, although this mimicking may be a 

 protection against other predaceous animals which fear 

 the bees' sting, or again it may just "happen so." The 

 eyes bulge out so that the head seems to be hollowed 

 between them ; the proboscis is stout, rather than long ; the 

 legs are strong and bristly. The larvae, also, are pre- 

 daceous, feeding upon other larvae in rotting wood, under 

 bark, fallen leaves, or in loose soil. 



DOLICHOPODID.E 



A technical point which distinguishes this family is that 

 the discal and second basal cells are united, there being no 

 separating cross-vein. They are usually less than .3 in. 

 long; have slender, tapering, usually metallic green abdo- 

 mens, and the tarsal part of the long legs are often rela- 

 tively quite long (See Psilopodinus, Plate LXVI). Prof. 

 Aldrich says: "This family perhaps surpasses any other 

 natural group of animals in the variety of secondary sexual 

 characters possessed by the males. These are ornaments, 

 and are paraded before the females, as are similar orna- 

 ments in the peacock and turkey-cock. They may occur 

 in the tarsi, tibiae, femora, wing-apex, face, third joint of 

 antenna, arista, palpi, and still other places. . . . The 



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