Insects and Insecticides 
23 
also makes the scarlet blotches on fruit and bark somewhat similar to 
the San Jose scale, but does not increase as rapidly. See Plate 3. 
Remedies. —Same as for San Jose Scale. 
Oyster-Shell Scale or Bark Louse. —^his is an elongated oyster- 
shell shaped scale of about the same color as the bark of the trees. 
It infests especially lilac and apple and pear trees. It passes the 
winter in the egg stage under the old scale. See Fig. ii. 
Remedies. —Dormant sprays are ineffective. Black leaf 40 (19), 
I part to 800 parts water, or kerosene emulsion (10), 8% kerosene, 
applied in the spring when eggs are hatching, will kill the young lice. 
Scurvy Scale. —This is a white scale insect. The female is about 
one-eighth of an inch long, flatter and more circular than the oyster- 
shell scale, and gives the bark a scurvy appearance. Male scales are 
much smaller and very slender. Like the Oyster-shell scale, it passes 
the winter in the egg stage under the old scales. When eggs are 
crushed they are of a deep purple color. 
Remedies. —Same as for Oyster-shell scale. 
Woolly Aphis. —Small reddish-brown lice attacking trunk and 
branches of the apple, especially on tender bark about wounds and on 
water-sprouts. They appear as bluish-white woolly patches which, 
when crushed, give a dark blood-red stain. The lice are covered with 
a woolly mass of white secretion. They suck sap from the bark and 
often cause an abnormal growth or swelling where they feed. See 
Fig. 12. 
Fig. 12.—Woolly Aphis, root form: a, small root showing swellings caused by the lice; 
b, wingless louse showing woolly secretion; c, winged louse. (After Saunders.) 
Remedies. —The white patches on the trunk and branches may be 
painted out with pure kerosene or crude petroleum (n), kerosene 
emulsion (10), or tobacco extract (19). 
If the lice become abundant on branches and twigs, spray with 
“Black Leaf 40,” i part to 800 parts water, with 3 pounds of soap to 
each ICO gallons to aid in penetrating the wooly secretion; or use 
kerosene emulsion (10) ordinary strength. .Use a high pressure and 
coarse spray, in order to wet through the wool. 
