Reports to the Board of Agriculture. 17 
every year. The eggs laid in the spring are placed on all kinds of 
Cruciferae ; the larvae feed upon the leaves ; they are dull, smoky 
yellow creatures, slightly hairy and spotted with black, the head and 
the six legs are also black ; there is also a distinct caudal foot and a 
row of tubercles along each side from which can be protruded curious, 
yellow glands ; when mature they reach about three-fourths of an 
inch in length. These larvae can be easily seen on the leaves, and 
are vulnerable at this stage. 
Preventive and Remedial Measures. 
All precautions should be taken to destroy as much winter shelter 
as possible. After a bad attack it would be advisable to burn the 
mustard straw, not at once, but after it has been allowed to stand 
some time in heaps in the fields ; the beetles would seek winter shelter 
there, and on firing the heaps they would be destroyed. 
All hedge trimmings and reedy growths along dykes should be cut 
and burnt during the winter. 
No experiments on a large scale seem to have been made in 
destroying the larvae upon the young plants when it is possible to get 
on the land. There is no doubt that the proper time to attack this 
pest is in its larval stage when feeding upon the young leaves. 
The fields should then be sprayed by means of a horse Strawsonizer 
with Paris-green wash ; the time to carry out this operation would 
depend upon the time the grubs are noticed on the leaves. 
The beetles also attack the young leaves, and would also be 
destroyed by the same wash. The beetles may also be collected, when 
present in numbers on the young plant, by dragging a long strip of 
tarred sacking attached to a light rod over the fields, and also by 
special machines. The beetles which attack the crop later on in the 
year may be kept in hand by preventing their movements from place 
to place. Towards the latter part of the year when so much damage 
is reported, the beetles do not seem inclined to use their wings, but 
migrate in a body along the ground from field to field. They can 
thus be “held up” like locusts by cutting a trench across their line of 
march, or by burning damp straw so that the smoke blows on to them. 
The employment of a shallow trench about a foot deep is the best 
plan to check them, especially it it can be filled or smeared repeatedly 
with tar. 
It is also important to keep horse-hoeing as long as possible 
between the rows ; by this means the pupae are turned out of the 
earth and are exposed to the attack of various birds. 
c 
