DISEASES OF INSECTS. 293 
those that emerged from one were all females, and those 
from the other, males*. He observed a similar fact take 
place with Misocampus Puparum®. One might conjecture 
from this circumstance, that as in the queen-bee‘, so in 
these Ichneumons, the eggs producing the two sexes were 
arranged separately in the ovaries. Reaumur has re- 
lated, that in one instance three or four males were pro- 
duced to one female; and in another four or five females 
to one male4. 
But though the great majority of insects are subject to 
this Scolechiasis® in their larva state, yet sometimes they 
are not attacked by the Zchneumon till they have become 
pupe@. Of this kind is one just mentioned (M. Puparum), 
which commits its eges to the chrysalis of the butterfly of 
the nettle, Vanessa Urtice: the moment this caterpillar 
quits its skin to assume that state, while it is yet soft they 
pierce it and confide to it their eggs‘. De Geer and 
others have supposed that this same Ichneumon attacks 
the Cocci and Coccinelle® ; but this probably is an erro- 
neous supposition. Cryptus Compunctor F¥. also attacks 
the pup of butterflies ®. 
If we consider the great purpose of PRoviDENCE in 
giving being to this tribe of destroyers—the keeping of 
insects within their proper limits,—we may readily con- 
ceive that this purpose is more effectually answered by 
destroying them in their preparatory than in their ultz- 
mate state, since at that time the laying of their eggs and 
a future progeny could not so effectually be prevented ;— 
2 De Geer i. 583—. > Tbid. ii. 884. 
© See above, p. 158. 4 Reaum. vi. 312. 
* Vou. i. p. 99. * De Geer ubi supr. 
& Ibid. 883. ® Linn. Fn. Suec. 1608. 
