192 ANIMAL LIFE 
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. 
Fie. 120.—Wasp (Polistes), with female Stylops para- 
site (#) in body. 
The larva of Thales- 
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 Stylopide 
present an interest- 
ing case of parasit- 
ism. The adult males are winged, but the adult females 
are wingless and grub-like. 
itself to a wasp or bee, and bores into its abdomen. 
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 
The larval stylopid attaches 
It 
Fig. 121.—The itch-mite 
(Sarcoptes scabei). 
(Fig. 121), which cause, in man, the disease known as 
the itch. 
