PLAHT-LICE. 



241 



the bottom of the cracks they have produced, more or less 

 protected by their wool from the cold. It is stated, on the 

 authority of Saimders in America, that this species also attacks 

 the roots of the apple-tree. AH such cases sent me in Britain, 

 and repeated investigations and inquiries, show that the lice 

 taken on apple-foots, some forming large galled patches, belong 

 to two other species^ — S. fodiens and PempTiigvs lactuarms. 

 Still, from American reports it seems that there is a ground 

 form of S. lanigera, like the ground form of the vine phyl- 

 loxera. Since the above was written I have received a valu- 

 able Eeport from the Agricultural College attached to Missouri 

 State University (U.S.A.), by Mr Stedman, in which he clearly 

 shows that a ground form of S. lanigera exists 



Prevention and Remedies. — We notice this disease chiefly 

 rampant in neglected orchards, where the trees are cramped 



Fio. 122. — Pldm Aphis (jlplig prwrei). 

 1, Viviparous female ; 2, ovigerons female. (Whitehead.) 



together, and the trunks and boughs covered with moss and 

 lichens. Keeping the trees properly thinned, with plenty of 



