APPLIED PESTS 
Professor Slingerland, of Cornell Uni- 
versity, has pointed out that in the ex- 
perience of some of his correspondents, it 
is very difficult to kill this green fruit 
worm after the apples are large enough 
to furnish food. It is probable that an 
early spraying would be effective and we 
recommend that four pounds of arsenate 
lead be adced to every 50 gallons of lime- 
sulphur or the tobacco extract applied 
just before the fruit buds open, or in 
water at the same time or a little earlier 
if there is no other pest requiring treat- 
ment. 
R. A. CooLex, 
Montana Circular No 17, 
Gypsy Moth 
Porthetria dispar Linn. 
By H. F.. WILson 
Like many other of our most serious 
pests this insect was imported from 
Europe and has been the cause of consid- 
erable trouble in this country. We do 
not as yet have this pest in the North- 
west, but everyone is warned to be on 
the lookout for it. 
The eggs are deposited in masses meas- 
uring three-fourths by one-half inches 
and containing approximately 500 eggs 
At first these egg masses are yellowish in 
appearance but during the winter, ex- 
posure to the weather causes them to be- 
come a dingy white. The individual eggs 
are about the size of a pinhead, and when 
first deposited are salmon colored, turning 
dark in the course of a few weeks. 
These eges hatch in the spring and each 
ege mass produces a mass of young dark 
caterpillars, which become full grown by 
midsummer. The caterpillars are decid- 
edly hairy and as they grow older as- 
sume a varied coloring along the back. 
Starting from the head, which appears 
mostly yellow, may be found a double 
row of five pairs of blue spots; these be- 
come very distinct on the larvae as they 
reach maturity and as the larvae are en- 
tirely distinct from any others which we 
have in the Northwest, they should be 
easily recognized if one meets with them. 
When full grown, which is in midsum- 
mer, the caterpillar spins a few strands 
of silk for support and changes to a chry- 
529 
salis, which is the pupal stage. In this 
stage they are dark reddish in color and 
thinly sprinkled with light reddish hairs. 
They remain in this stage tor about two 
weeks and then change to the adult in- 
sect. The female moth is white with nu- 
merous black markings, is quite robust 
and moves about very sluggishly. 
The male is brownish yellow with some- 
times a greenish tinge. They fly about 
during the day and after mating with the 
females live but a very short time. The 
males measure about one and one-half 
inches from tip to tip of wing. The fe- 
males measure about two inches but do 
not fly and therefore do not spread as 
rapidly as they might After copulation 
takes place the females deposit their eggs 
and die. 
This pest is probably mostly distributed 
by egg masses on nursery stock, but as 
the larvae have a habit of spinning webs 
and dropping from trees they are often- 
times carried on automobiles and other 
vehicles for long distances. 
The gypsy moth caterpillar will attack 
all fruit, shade and woodland trees. Apple 
trees seem to be preferred above all 
others. 
There are many natural enemies of 
the gypsy moth and in Europe these are 
sufficient to keep it under control. 
In the United States it will be neces- 
sary to wage combat until such natural 
enemies as are being imported can in- 
crease to numbers corresponding to those 
of the gypsy moth. 
Remedies 
The most effective time to catch this 
insect is in the egg mass. These wher- 
ever accessible, can be killed by soaking 
them in creosote. When the caterpillars 
are quite small they can be poisoned 
with arsenate of lead at the rate of 10 
pounds to 100 gallons of water. This can 
be applied with any of the common force 
pumps. 
Natural Enemies 
(The numerous parasites which the en- 
tomologists of the Department of Agricul- 
ture have imported, it is stated, are be- 
ginning to control this pest.—Eb.) 
