DISEASES OF INSECTS. SRT 
Acartasis seems a disease almost as universal amongst 
insects as Scolechiasis ; with this difference however, that 
Acarimost commonly take their station upon them in their 
perfect state. You have doubtless often observed the com- 
mon dung-beetles (Geotrupes Latr.) covered on the under- 
side of their body with small mites (Gamasus Coleoptrato- 
rum Latr.) which look as if they were engaged in suction 
—they are often so numerous that no part is uncovered ; 
they also attack other beetles?, and are sometimes found 
on humble-bees. They are easily disturbed, run with 
great swiftness, and may often be seen in hot-beds and 
fermenting dung prowling in search of the stercora- 
rious beetles. But the most remarkable insect of this 
kind is the Uropoda vegetans: it derives its nutriment 
from the insects it assails not by its mouth, but by means 
of a long anal pedicle by which it is attached to them. 
De Geer found these in such numbers upon a species of 
Leptura, that its whole body was almost covered with 
them; they hung from the legs and antennee in bunches, 
and gave the animal a most hideous and disgusting ap- 
pearance. Under this load of vermin it could scarcely 
walk or move, and all its efforts to get rid of them were 
in vain: many were attached to its body and to each 
other by their anal pedicles, but others had cast them 
off and were walking about. When put into a glass 
with earth, they began to abandon their prey, so that 
in a few days it was quite freed from its plagues. He 
found that these parasites lived long in alcohol?. 
If you inquire—How are these mites originally fixed by 
their pedicles? it seems most probable, that as the He- 
* Fister particularly. » De Geer vil. 126—. 
Q 2 
