INSECT ENEMIES. 101 
(See figure 70.) The numerous punctures they make 
in the bark of the tender shoots produce warts or ex- 
crescences on the bark, till the limbs become sickly, the 
leaves turn yellow and drop off, and sometimes the whole 
tree dies. 
Remedies.—The lady-bugs and their larve, the larve 
of the Syrphus and lace-winged flies, ard the little chal- 
cid fly (Aphelinus mali, Hald.), all feed on these plant- 
lice. ‘The old bark should be scraped off wherever it 
makes a harbor for them, and then with a stiff brush 
they should be treated to a solution of lime and sulphur 
(five pounds of lime to one of sulphur in two gallons of 
water, heated till the sulphur is dissolved). The earth at 
the roots, as far as practicable, should be exchanged for 
fresh soil. A pound of potash in a gallon of water is 
effective. Another application is made, melting three 
ounces of resin with the same quantity of fish oil, and 
applying it warm with a paint brush. Spiders spin their 
webs over and feed on them at their leisure. 
4, THE SEVENTEEN-YEAR CICADA, commonly called 
Locust (Cicada septendecim, Linn.).—This insect de- 
rives its name from the time it requires to pass through 
its several changes. The long intervals at which they 
appear, and the little damage they do to the quince, make 
any extended description of the seventeen-year locusts, 
however interesting, quite unnecessary here. It may be 
found in any good work on entomology. The damage 
done by these insects can not be prevented. They can 
not eat, and the only injury they do above ground is 
confined to the small branches in which they deposit 
their eggs; but when they go over a whole tree in this 
way it becomes a serious matter. These branches die 
and fall off, and there is nothing to do but trim off the 
rough ends with a smooth cut. In the larva state they 
do much injury to the roots of trees. The birds, poultry, 
ete., destroy many. The plow destroys more in culti- 
