Q4 Farmers’ Bulletin 1169. 
the plant, and by the curling and the abnormal falling of the leaves. 
When this honeydew is very copious, the black film which forms upon 
it gives the leaves and other portions of the plant a dirty appearance 
and clogs their breathing pores. Many aphids also produce various 
growths, called galls, on the tree parts they inhabit. 
Control._—N otwithstanding their great numbers, aphids are usually 
incapable of doing permanent harm to an otherwise vigorous tree. 
They are never excessively abundant for long periods, being deci- 
mated by their numerous insect enemies, and a sharp change in the 
weather to hot and dry makes their disappearance as sudden as their 
appearance. Hence treatment, which involves labor and expense and 
requires an adequate spraying equipment, is in most cases safely dis- 
pensed with. When conditions warrant, however, it is possible and 
not difficult to check aphid injury artificially, as described under the 
several species. The strength of the solution used should be in pro- 
portion to the resistance of the plant to be sprayed; that is to say, the 
more delicate the plant the weaker the solution. Thoroughness and 
early application, before the leaves begin to curl, is indispensable to 
success. Often a forceful stream of water out of a hose directed 
against the aphids will dislodge and destroy them. Cooperation with 
neighbors in the purchase and operation of equipment, or in the em- 
ployment of reliable and competent persons who make a specialty of 
the work, is desirable where feasible. 
NORWAY MAPLE APHIS.” 
How injurious —This aphis frequently occurs in large colonies dur- 
ing much of the summer on the underside of Norway maple leaves, 
which are evidently its favored food. It is a copious producer of 
honeydew, which accumulates on the leaves and the pavement beneath 
them. Many of the leaves either develop brown blotches or fall off 
later, littering the ground and temporarily disfiguring the tree, be- 
sides seriously checking growth generally. 
How recognized.—The leaves are off color, with honeydew, a sticky 
sweetish liquid, on them and on the ground below them, and many, 
mostly wingless, yellowish green, brown marked, licelike insects of 
various sizes with reddish eyes and long hairy antenne are found on 
the underside of the leaves. 
Habits—Our knowledge of the habits of this insect, beyond what 
has been indicated above, is limited. Fortunately, what is known 
helps considerably in controlling the insect. 
Remedy.—A spray of 40 per cent nicotine sulphate (p. 18) mixed 
with soap and diluted in the usual manner will prove quite effective, 
58 Periphyllus lyropictus Kess. 
—orr 
