f 9 ] 
Yellow Butterfly ., were common about London ; the naturalift 
ma y» perhaps, wait fix years before he fees another. 
The moft probable caufes are, the peculiarity of the wea¬ 
ther, and the plenty or fcarcity of the enemies of the Infeft ; 
for almoft every different fpecies of Infedt has its peculiar 
enemy, and none more than the Caterpillars of Moths and 
Butterflies. As to the former, warm and dry weather are uni- 
verfally allowed to promote the generation of Infefts ; violent 
winds, heavy and long continued rains, or extreme cold, are, 
on the contrary, fuppofed to check and deffroy them. It is, 
however, wonderful to obferve, with what addrefs they fecure 
themfelves from the effects of the two former; fuch as feed on 
the boughs, on fuch occafions creep from them to the large 
branches or body of the tree, where they reft unfhaken ; and 
thofe who refide in webs are fo fecured as to fufter little injury 
from any of thofe caufes. 
We obferved, that Caterpillars had many enemies. Birds 
of various kinds feed on them : the ftomach of a cuckow that 
was fhot, was found full of the Caterpillars of the Buff-tip 
Moth ('Ph. Bucephala). Mr. Church, Surgeon, oflflington, 
has obferved birds very bufily feeding on the Caterpillars of 
this very Moth, and carrying them to their young. The Ear- 
\vig is a great deftroyer of Caterpillars. But their grand enemy 
is the Ichneumon Fly *, a proof of whofe deftrudive powers I 
experienced 
There are various kinds of flies which pierce the fkin, and depofit their 
eggs in the bodies of Caterpillars; but the moft common is the Ichneumon Fly. 
Tt,e e S 3 s t,lus quickly produce fmall maggots, which feed on the body of 
the Caterpillar, taking care to eat that part only which lies immediately under 
the flcin, whereby they avoid injuring thofe parts which are effential to life; 
tor, fhould the Caterpillar be deftroyed, they alfo would perilh. Till the period ' 
