as a nidus for a black fungus, which greatly disfigures the leaves 
and renders them unhealthy because it blocks up the stomata, or 
“breathing pores”, of the plant. The insects are easily controlled 
in the greenhouse by fumigation with hydrocyanic acid gas, but 
out-of-doors they are more difficult to manage, because the adults 
are very active and fly away as soon as sprayingcommences, only 
to return again when the coast is clear. Persistent spraying with 
any of the contact sprays— soap, nicotine, or kerosene emulsion- 
will eventually exterminate them. Care should be taken when 
applying the spray to reach the under side of the leaves. 
Oyster-Shell Scale. {Fig. 1 .) These scales obtain their name 
from the fact that they resemble an oyster 
shell in outline. They are a serious pest on 
apple, willow, lilac, and other trees and 
shrubs. The infested plants should be 
sprayed about the second week in June 
when the young scales are emerging from 
the protecting scales of the parent insects. Use kerosene emul- 
sion. 
San Jose Scale. {Fig. 2.) This is another scale insect, more rounded 
in outline than the preceding, that 
is best combated by winter treat- 
ment. It infests practically all fruit 
trees and is frequently found on 
roses. It should be sprayed in fall, 
as soon as the leaves are off the 
trees, with commercial lime-sulphur 
(winter strength) or with a miscible 
oil, such as scalecide, using one part to fifteen parts water. It is 
advisable to give another spraying in the spring before the buds 
open, if the trees are badly infested. 
Aphids: Plant Lice. ( Fig 3.) Many different species of aphis 
infest plants, and there is scarcely 
any kind of plant that is immune 
from their attack. When they in- 
fest fruit trees, or arborescent and 
shrubby plants generally, their 
numbers may be materially re- 
duced by spraying with lime-sul- 
phur (winter strength; before the 
buds open in spring. This treat- 
ment destroys their eggs. Later on in the season they may be 
controlled by spraying with nicotine or soap solution. A typical 
aphis is illustrated at Fig. 3. 
All of the above are sucking forms, and to do any good the 
