DISEASES OF INSECTS. 215 
the spider, exhausted by this last effort, had fallen dead 
to the bottom of the glass. It cannot be asserted posi- 
tively that this suspension of the larva of the Ichneumon 
in the centre of the web always takes place; but if it does, 
as seems most probable, it shows that this little parasite 
is endowed with an instinct which causes it so to act upon 
. the spider as may induce it to spin a web so nicely timed 
as to be sufficiently complete at the period of its death 
and of the change of the Ichneumon, for the latter to cast 
it down and assume its station?. 
But the great buik of the parasitic Hymenopterous de- 
vourers of larvee have their assigned station withzn the bo- 
dy. As Entomologists in breeding insects have paid their 
principal attention to Lepzdoptera, it necessarily follows 
that their Ichneumon infestors must be most generally 
known; but doubtless the larvee of the other Orders are 
not wholly liberated from this scourge: they also require 
to be kept within due limits, and have their appropriate 
parasites. Some, however, in most of them have been 
detected ; of which I shall now proceed to state to you 
the most interesting examples, beginning with the Co- 
leoptera. 
~ Alysia Manducator Latr.», remarkable for having man- 
dibulze that do not close, and toothed at the end, usually 
attends masses of dung, both of man and cattle, probably 
for the purpose of depositing its eggs in some of the Co- 
leopterous larvee that inhabit it. Mr. Stephens, one of the 
most accurate obserttes as well as one of the best Ento- 
mologists of the present day, informs me that he once 
captured three specimens of Timarcha tenebricosa, from 
® De Geer ti. 863—. b’ Panzer Fn. Germ. Init. xxi. 4. 
