OF THE LARVA STATE. 65 
breeding these flies in a state of confinement, and 
introducing to them some Cabbage Caterpillars, 
their proceedings in depositing their eggs may be 
observed. We have more than once seen one of 
these little flies select a Caterpillar, and perch upon 
its hack, holding her oyipositor ready brandished to 
plunge between the rings, which she seems to prefer. 
When she has thus begun laying her eggs, she does 
not readily take alarm; but, as Reaumur justly 
remarks, will permit an observer to approach her 
with a magnifying glass of a very short focus. 
Having deposited one egg, she withdraws her ovi- 
positor, and again plunges it, with another egg, into 
a different part of the body of the caterpillar, till 
she has laid in all about thirty eggs. It is not a 
little remarkable, that the poor caterpillar, whose 
body is thus pierced with so many wounds, seems to 
bear it very patiently, and does not turn upon the 
fly, as he would be certain to do upon another 
caterpillar, should it venture to pinch him, a cir- 
cumstance byno means unusual. Sometimes, indeed, 
he gives a slight jerk ; but the fly does not appear 
to he at all incommoded by the intimation that her 
presence is disagreeable. 
« The eggs, it may be remarked, are thrust suffi- 
ciently deep to preyent their being thrown off when 
the caterpillar changes its skin ; and being in due 
time hatched, the grubs feed in concert on the living 
body of the caterpillar. ‘The most wonderful cir- 
