576 Report of the Entomologists of the 



Remedial measures. — There seems to be no satisfactory reme- 

 dial measure which can be made practical in large nurseries. 

 The colonies above ground are said to be easily destroyed by most 

 of the standard insect washes. The root colonies do not thrive 

 in heavy, damp ground. For this reason, Prof. Comstock states,* 

 it has been suggested that '' the earth around the crown be hol- 

 lowed into a sort of basin in order that the water may collect 

 there.'' Applying insecticides such as strong soap suds or kero- 

 sene emulsion is said to be an effective remedy. Hot water is 

 also recommended for this purpose. Experiments conducted at 

 this Station show that keeping the soil about infested roots con- 

 stantly wet with cold water does not kill the lice or seriously 

 delay their increase. 



S"[:iMMAUY. 



The most important points stated above may be briefly sum- 

 marized as follows: The woolly aphis belongs to the well-known 

 family of insects which includes the plant lice. It is easily dis- 

 tinguished because of the white woolly secretion. It has long 

 been known as an injurious insect in both Europe and America. 



This insect is well distributed throughout the apple-growing 

 sections of the country. 



It attacks the roots of the trees, forming galls on them; also 

 the trunks and branches, causing pits and scars on the bark 

 of the former, and withering and death of the latter. Lice 

 may go from the roots to the trunks and branches. Most of the 

 lice are wingless, although at certain times of the year winged 

 individuals appear. Eggs are produced only once a year, and 

 these remain on the trees over winter, hatching in the spring. 

 Some of the lice also hibernate. 



The woolly aphis is of especial importance to nurserymen, as 

 it causes more injury to nursery stock and young trees newiv 

 planted in the orrhnrd than to older trees. It is also largely bv 

 means of nursery stock that this insect is carried from one part 

 of the country to another. 



~ "^'Report Uuited States Dapartinentof Agriculture, 1879, p. 260. 



