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GROUP CALYPTRATE MUSCIDJE. 



The insects in this group are distinguished from 

 another group, the Acalyptrate muscidae (fruit 

 flies), by the presence of well-developed squamaB 

 (see Note 3 b, below) and by the venation of the 

 wings. 



In the calyptrate muscidae are several families. 

 The general characteristics are as follows: — (1) The 

 larvae are without a differentiated head; the jaws 

 are the most prominent feature of the anterior end. 



(2) The pupae are always enclosed in a hardened, 

 seed-like puparium — that is, the last larval skin, 

 which acts as a ''cocoon." (Plate 44, Fig. 3.) 



(3) The adult (a) emerges from the puparium by 

 pushing off a circular lid; (b) there is a small 

 wing-like structure at the base of the wings called 

 a squama — these squamae cover, or partially cover, 

 the halteres or balancers; (c) the males have eyes 

 which meet across the head and form the greater 

 part of it. 



A. Family Tachinidae. The bristles of the an- 

 tenna are quite bare. (Plate 43, Fig. 6 a.) ex.\ 

 Tachina, which is parasitic on caterpillars. 



B. Family Sarcophagidae, or ''flesh flies." The 

 bristle of the antenna is feathered, but only at 

 the base: (Plate 43, Fig. 6 b.) ex.: Sarcophagay 

 parasitic on locusts (short-horned grasshoppers). 



C. Family Dexiidae ("metallic green flies"). The 



