192 



ANIMAL LIFE 



FIG. 120. Wasp (Polities), with female Stylops para- 

 site (a;) in body. 



ism. 



The larva that hatches from this egg creeps along this 

 burrow until it reaches its victim, and then fastens itself to 

 the horn-tail larva, which it destroys by sucking its blood. 



The larva of TJiales- 

 sa, when full grown, 

 changes to a pupa 

 within the burrow 

 of its host, and the 

 adult gnaws a hole 

 out through the bark 

 if it does not find the 

 hole already made by 

 the Tremex." 



The beetles of 

 the family Stylopidae 

 present an interest- 

 ing case of parasit- 



The adult males are winged, but the adult females 

 are wingless and grub-like. The larval stylopid attaches 

 itself to a wasp or bee, and bores into its abdomen. It 

 pupates within the abdomen of the 

 wasp or bee, and lies there with its 

 head projecting slightly from a su- 

 ture between two of the body rings 

 of its host (Fig. 120). The adult 

 finally issues and leaves the host's 

 body. 



Almost all of the mites and ticks, 

 which are more nearly allied to the 

 spiders than to the true insects, live 

 parasitically. Most of them live as 

 external parasites, sucking the blood 

 of their host, but some live under- 

 neath the skin like the itch-mites 

 (Fig. 121), which cause, in man, the disease known as 

 the itch. 



FIG. 121. The itch-mite 

 (Sarcoptes scabei). 



