Il.'f PLANT LICE: DESCRIPTIONS, ENEMIES AND 



TREATMENT.* 



V. H. LOWB. 



SUMMARY. 



Plant lice are among the most important of the injurious in- 

 sects. They may be found every year in the orchard and garden, 

 but seldom in such numbers as during the past season. 



Plant lice do not devour the tissue of the host plant, but suck 

 the sap by means of their tube-like mouth parts. They swarm 

 upon the open leaf-buds and on the under surfaces of the leaves, 

 causing them to curl and to become otherwise distorted. These 

 insects multiply with great rapidity, but are held in check to a 

 certain degree by numerous predaceous and parasitic insects. In 

 most species the young are born alive during the spring and sum- 

 mer, eggs not being produced until fall. 



As plant lice suck their food, Paris green and similar poisons 

 cannot be depended upon when used in the ordinary manner. 

 Some external irritant must be used instead. Numerous insecti- 

 cides of this nature are recommended. One of the most impor- 

 tant is good whale-oil soap. Experiments during the past season 

 show that one pound of whale oil soap to seven gallons of water 

 will kill plum and currant lice. The solution should be applied 

 in a fine spray to the under surface of the leaves. It is impor- 

 tant that the work be done very thoroughly. The first appli- 

 cation should be made as soon as the lice appear in the spring, 

 which will be soon after the leaf-buds open. A second or third 

 application may be made, as occasion demands. 



•Reprint of Bulletin No. 18». 



