THE STUDY OF INSECTS. 



frontal suture is present. The legs are broadly separated 

 by the sternum ; they are comparatively short and stout ; 

 the tarsal claws are strong and are often furnished with 

 teeth. The winged forms vary greatly in the venation of 

 the wings. The veins near the costal border are usually 

 strong while the others are weak. Figure 595 represents 



+vn, 



FIG. 505 Wing of Olfersia. 



the venation of Olfersia. In this genus veins 111,+, and 

 III 4 -f- s separate near the base of the wing. In Hippobosca 

 they separate at or beyond the middle of the wing. 



Even more remarkable than the parasitic life of the adult 

 flies is the mode of reproduction of these insects. The egg 

 is hatched within the body of the parent, the larva is nour- 

 ished in this position till it is full-grown, and is not born till 

 it is ready to change to a pupa. This mode of reproduction 

 is also characteristic of the two following families, which are 

 frequently on this account classed with this one as a division 

 of the Diptera, termed Pupipara (Pu-pip'a-ra). 



The most common member of the Hippoboscidae is the 

 Sheeptick, Melophagus ovinus (Me-loph'a-gus o-vi'nus). This 

 is a wingless species (Fig. 596), which lives upon 

 sheep. Hippobosca equina (Hip-po-bos'ca e-qui'na) 

 is winged and lives on the horse. Olfersia ameri- 

 cana (Ol-fer'si-a a-mer-i-ca'na) is also winged and 

 is common on owls and other birds. The species 

 of the genus Lipoptera (Li-pop'te-ra) are winged 

 at first and live on birds ; later they migrate to quadrupeds, 



FIG. 596. 



