124 TURNIP. 
attention to the mischief that was going forward, and also helping 
to lessen the amount. The white bodies beneath infested Turnip 
leaves, having the appearance of cocoons covered with mould, and 
with the contents in brown decay in the centre, are also worth 
attention. 
The habit of life of the Diamond-back is for the female moths for 
the most part to lay their eggs on the under side of the leafage of the 
attacked plants, as Turnips, Swedes, Cabbage, Charlocl, or allied 
crop-plants, or weeds. 
The caterpillars, when full-grown, are about half an inch long, and 
somewhat spindle-shaped, that is, taper towards each end. The 
colour is variable, but commonly of an apple-green, and when near 
full growth the head is usually grey or yellowish, and marked with 
small black dots, and the next ring has a number of very minute black 
specks. When young the caterpillar is often yellowish or greyish, 
with black head. Each of the first three segments bears a pair of 
claw feet, and there are four pairs of sucker feet beneath the body, 
and another pair which are set out slantingly from each other at the 
tail. When alarmed the caterpillar can let itself down by a thread, up 
which it returns again at pleasure. 
Where severe attack is present, it may be distinguished from other 
insect mischief by many of the leaves being what is termed ‘“ lace- 
worked.’ The caterpillars feed on the under coat of the leaf, so that 
to a certain extent the upper coat may often be found remaining 
merely as a thin film. But very often, from the caterpillars not 
feeding on the veins of the leaves, these will be found remaining, with 
the thin connecting upper coat of the leaf so broken away in drying 
that the network of veins greatly resembles a piece of coarse pale 
brown lace, and the appearance may be taken as a guide to the kind of 
infestation that has done the mischief. 
The caterpillars spin up in about four weeks from hatching, and 
form cocoons on the under side of the leafage of their food-plants, or 
in any convenient place on or near it. These cocoons are often of 
such a mere open network that the form of the chrysalis can be seen 
through the web of threads. The time spent in chrysalis state may 
vary a good deal, as from rather over one to about three weeks ; the 
chrysalids from the last brool of the year remain in this state through 
the winter. 
The size of the moths is only about or rather under two-thirds of 
an inch in the spread of the wings, and to ordinary observation they 
appear as brownish-grey moths, about the size of ‘‘ furniture moths,” 
but long and narrow in shape. When at rest, and the upper wings 
laid along the back, with the edges meeting, the pale patterns along 
these edges form diamond-shaped marks, whence the English name 
