94 
TURNIP-FLY. 
of which, if I were to relate, with the accorapanimeiit which 
I must add that they have all turned out to he failures, 
surprised that they should hitherto have escaped my observation. This leaf 
was removed with the eg'gs upon it and placed in water, and its place supplied 
by a fresh one, which, on the following day, had three eggs upon it, and the 
third leaf four eggs, each of which leaves was placed separately in water. The 
fourth leaf T suffered to remain with the insects a week, supplying it with fresh 
water daily, and at the end of that time it had thirty-one eggs upon it. Tn 
two other glass tubes I confined single pairs of insects, with a leaf in each, 
upon which I never found more than a single egg deposited on the same day, 
and in those leaves taken from the field with larvge in them (some containing 
six) no two of them were of the same growth. I found great difficulty in pre- 
serving the leaves during the length of time necessary for the hatching of the 
eggs, and as it would have been impossible to have preserved them long enough 
for the feeding of the larvse, I began to despair of success, until I observed 
that in those leaves taken with larvae in them from the field, it was not uncom- 
mon for the larva to leave the burrow it had first commenced, and travelling 
(which, from its formation I had supposed it incapable of doing) to a distant 
part of the leaf, form a new one. About the time, therefore, when I expected 
the eggs to hatch, I placed fresh leaves by the side of the old ones, to which 
the young larvae soon found their way, and lodged themselves. The egg 
hatches in ten days from the time it is laid, and the larva immediately begins 
to eat its way into the leaf, and form a burrow by feeding upon the pulp be- 
tween the upper and under surface of the leaf, which, however, is not easily 
perceptible to the eye unless held up against the light, although the track is 
sufficiently obvious after the larva has left it, and it has become dry. The 
larva is full fed, and goes into the earth at the end of sixteen days, burying it- 
self about an inch and a half below the surface, and in such a situation, that 
the turnip leaf above may afford shelter in case of rain. I have reason to be- 
lieve that it remains in the earth about a fortnight before changing into the 
perfect beetle. Some of the first specimens of larvae and pupse which I took in 
the field, I placed in finely pulverized and very dry earth, and in a few days 
they were shrivelled up ; the others I also put into fine earth and saturated it 
with water. Unfortunately there was no opening at the bottom of the cup ; 
and the next day, perceiving that the earth was still saturated with water, I 
drained it and removed the larvae, but they were all dead ; this accident may 
serve to account for the scarcity of the insects after very wet seasons. I have 
been equally unfortunate in my last attempt to ascertain the precise time be- 
tween the larva and the perfect insect, for I covered the earth in which I had 
placed them so closely, on account of their small size, to prevent them from 
