26 
Mr. Henry Le Keux on the Turnip Fly. 
shrivel up when the leaf becomes dry. Being still at fault as to 
the origin of the larvae, I captured ten males and ten females in 
pairs, and inclosed them in a glass tube covered at each end with 
gauze wire, into which I introduced a single leaf of turnip, with 
water to keep it fresh ; by this means I was enabled to examine the 
insects and leaf on all sides with a magnifying glass at any time 
without disturbing them. Having, previous to introducing the leaf, 
ascertained with a strong magnifier that there were no eggs or 
larvae upon it, on the following day I had the satisfaction to per- 
ceive five small, smooth, oval-shaped eggs adhering to the under- 
side of the leaf, and so nearly resembling it in colour that I was no 
longer surprised that they should hitherto have escaped my obser- 
vation. This leaf was removed with the eggs upon it and placed 
in water, and its place supplied by a fresh one, which, on the fol- 
lowing day, had three eggs upon it, and the third leaf four eggs, 
each of which leaves was placed separately in w’ater. The fourth 
leaf I 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. In 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 larvae in them (some containing six) no two of them 
were of the same growth. I found great difficulty in preserving 
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 larvae, I began to despair 
of success, until I observed that in those leaves taken with larva in 
them from the field, it was not uncommon 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 ex- 
pected the eggs to hatch, I placed fresh leaves by the side of the 
old ones, to which the young larvm soon found their w r ay 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 between the 
upper and under surface of the leaf, which however is not easily 
perceptible to the eye unless held up against the light, when it ap- 
pears as represented in the drawing at A., although the track is 
sufficiently obvious after the larva has left it, and it has become dry, 
as shown at B. The larva (of which a magnified specimen is shown 
in the drawing) is full fed, and goes into the earth at the end of 
sixteen days, burying itself about an inch and a half below the sur- 
