90 Farmers’ Bulletin 1169. 
gall. Within this gall she reaches maturity and gives birth to the 
numerous living lice that we find filling it in midsummer. The 
characteristic feature of the gall made by this species is that its 
mouth, which later serves as an outlet for its inhabitants, runs 
crosswise of the leaf stem. This seasonal history applies to the 
South where the study was made, and while in the main it doubtless 
applies also to the North 
there may be some sea- 
sonal differences. 
Remedies.—For reasons 
advanced in connection 
with other less injurious 
insects, circumstances are 
‘arely such as to merit or 
justify control measures. 
In extreme cases, however, 
the application of remedial 
measures might be con- 
sidered. Depending on 
conditions, control in such 
cases may be centered 
either on cruciferous plants 
or on poplar trees. In the 
latter, removing and burn- 
ing of the infested leaves 
or dipping them in kero- 
sene to kill the insects 
would greatly assist in re- 
ducing their numbers. 
HICKORY GALL-INSECTS.” 
Evidence of infesta- 
tion.—In the spring, when 
Fic. 63.—The hickory phylloxera (Phyllowera sp.):; the leaves and twigs are 
Sn Oo a ae forming on the hickory, 
these are frequently more or less deformed by peculiar tumorlike 
growths of various shapes and sizes (fig. 63). These are caused either 
by gall-lice related to the grape phylloxera or by gall midges. When 
these galls occur in large numbers they disfigure the affected parts 
and attract attention, but this rarely affects the vitality of the tree 
materially. Their great variety—30 species of Phylloxeridae and 
28 of Itonididae, beside 3 mites (Eriophyidae) are listed under 
hickory in the latest work on American gall -insects—and_ their 
6 Families Phylloxeridae and Itonididae. 
ht ee 
