OF THE TURNIP CATERPILLAR. 
459 
afterwards another brood attacked the young turnips, then just ready 
to be hoed out. The insects commenced their attack behind the hoers, 
upon the best plants selected to stand, and in a very few days w r ould 
have devoured the whole.” Mr. Woollard, on observing this, imme¬ 
diately ordered the men to cease hoeing, resolving to allow the cater¬ 
pillars a full feast, hoping thereby to save a share of the crop for his 
sheep. He was led to adopt this management from observing, that, as 
the insects came forth simultaneously on the turnips, it was probable 
their life as caterpillars would be short, and that the then existing 
brood would quickly vanish. In this surmise he was right; for, having 
kept some in confinement, he found that they continued ravenous and 
as caterpillars for from fourteen to twenty days, after which they retire 
beneath the surface of the ground, and very soon are changed into 
chry scd idee. 
In the chrysalis state they remain for a period of between two and 
three weeks, when they come forth as a hymenopterous fly, having a 
yellow breast and abdomen ; corslet or body (to which the legs and 
wings are joined) black; eyes lateral, large, and black ; wings diapha¬ 
nous, with black veins, and a long marginal mark of the same hue on 
the outer side of each. 
The fly preserved and presented to us by Mr. Woollard is somewhat 
mutilated, so that neither antennae nor other members of the mouth can 
be accurately described by us; but there is a remarkable liorn-like 
appendage, the remains of the antennae, protruding from the front of 
the head. The fly is nearly half an inch in length, and has some dis¬ 
tant resemblance to the yellow-bodied flies (Sccdophagi stercoraria ) 
which appear on recently-laid heaps of dung in gardens or fields. We 
will show the fly to some able entomologist, w T ho may favour us with 
a better account hereafter for publication. 
The manners and haunts of the perfect insects are yet to us un¬ 
known ; but it is probable that, after sexual cohabitation and deposi¬ 
tion of eggs by the female, they become food for swallows and other 
insectivorous birds, and soon insensibly perish. 
But how can we defend our crops from their attacks ? is the grand 
practical question. The discovery of this is the proper business of the 
entomologist, and the only use (besides rational amusement) of the 
study and knowlege of the science. 
When they are plentiful in one season, it is likely they will abound 
in the next, unless some accident of w 7 eather proves destructive to their 
eggs during winter. As those noticed by Mr. W. appeared imme¬ 
diately after the hoe, it may be that the eggs are contained in the dung, 
and its exposure and comminution on the field brings them to life. 
