6 



important in the limitation of this insect. It is within the bounds of 

 possibility that the fungus might be cviltivatecl artificially and be used, 

 when weather conditions are favoral)le, in the control of this pest. 



BIETHODS OF CONTROL. 



In some instances natural enemies of this plant-louse have done 

 efficient service. Seldom, however, do they destroj^ the insects suf- 

 ficiently early in the season to save a crop. In the course of time, 



Pi(i. 3.— A lace-wins Hy (Chriisopa ociilata): a. orss ; h. full-grown larva : c. foot of same: a, same 

 devouring pear-tree psylla ; c, cocoon : f, adult insect ; o. head of same : It, adult, natural size- 

 all enlarged except h, which i-; natural size (from Marlatt). 



many years in all likelihood, these enemies may become more effect- 

 ive ; hence, in view of the fact that the extermination of the species 

 even in a limited area is a practical impossibility, anything that 

 can be done that will destroy the louse without harming its insect 

 enemies is advisable. If this is to be accomplished it affords in itself 

 a reason for the rejection of insecticides, none of which are in all 

 respects satisfactory. ^ 



Kerosene-soap emulsion, a standard remedy for plant-lice, care- 

 fully prepared and diluted with about twelve parts of water, and 



1 For the benefit of some persons wfio are not wholly familiar with the feeding 

 liabits of this species it should be stated that it obtains nourishment by suction, 

 and can not therefore be reached by means of internal or etomach poisons such 

 as Paris green and other arsenicals. 



