174 



PROTECTION AGAINST INSECTS. 



not entail a greater expenditure of time, trouble, and money 

 than the results will justify. 



In general, the following rules may be adopted : 

 (a) Collection and destruction oj eggs, larvae, pupae or perfect 

 insects. This is unfortunately impracticable for most injurious 

 species, or is too protracted a method, except in the case of 

 perfect insects. A knowledge of the life-history of any 

 particular insect will inform the forester of the stage in which 

 it is best attacked, but for practical reasons a season should 



Figs. 69 and 70. -Caterpillar shears (reduced}. 



Front. Back. 



a. Cord. I. Spring, c. Moveable blade. 



be chosen for their destruction, when the requisite labour- 

 force is available. 



Collections of insect-eggs can be made only when they are 

 laid in clusters, as those of mole-crickets, the lackey-moth, 

 and the black-arches moth. The simplest method of destroying 

 the latter is to crush them on the tree. 



The larvae of Lepidoptera and sawflies may be collected by 

 shaking the attacked poles or saplings, or by beating with 

 a mallet or the butt- end of an axe at the base of the branches 

 of trees, so that the larvae fall on to a cloth spread on the 

 ground. Care must be taken to protect the hands of collectors 

 by gloves against hairy caterpillars, which, when handled, 

 cause inflammation. When in groups on the trees, larvae 



