270 BOAED OF AGRICULTURE. [Pub. Doc. No. 4. 



will feed for days without apparent injury upon trees which have 

 been sprayed with Paris green or London purple in a solution so 

 strong as to somewhat burn the leaves. In fact, the committee, in 

 the spraying which they are carrying on at present, have found it 

 necessary to use arsenate of lead in as strong proportion as ten 

 pounds to one hundred and fifty gallons of water. The well- 

 known vitality of previously introduced European injurious in- 

 sects is apparently increased to a striking degree by this species, 

 while the fact that it feeds on nearly all plants renders it a much 

 more serious pest than any of its forerunners. Under these cir- 

 cumstances, therefore, any course other than energetic and well- 

 directed effort to keep the insect within its present boundaries will 

 be short-sighted in the extreme, although it is very doubtful to my 

 mind whether absolute extermination will or can ever be brought 

 about. 



