Destruction of Mustard Beetle. 



525 



would seek winter shelter there, and on firing the heaps would 

 be destroyed. 



All hedge trimmings, and reedy growths along dykes, should 

 be cut and burnt during the winter. Sufficient experiments on a 

 large scale do not seem to have been as yet 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 straw- 

 soniser with Paris-green wash ; the time to carry out this opera- 

 tion would depend upon the time the small 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 field 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 if 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. Mustard 

 should always therefore be drilled far apart when grown for 

 seed ; more than a foot should be allowed between each row. 

 Not only can the crop then be easily horse hoed, but special 

 machines can be taken across the fields between the rows to catch 

 the beetles. Wooden scoops, with tar or soft soap smeared over 

 the insides, may be arranged so as to be pulled through the 

 field either by hand or horse power and so collect the beetles. 



The early spraying with some arsenical wash so as to kill the 

 larvae and beetles, is, however, most to be recommended. 



