10 
upon the leaves, but these must be used in unusual strength. We 
have found three pounds of arsenate of lead to fifty gallons of w^a- 
ter sufficient to kill the full-grown caterpillars. On one occasion 
? tree nearly fifty feet high ^vas effectively sprayed by the aid of a 
twenty-eight-foot ladder and a twelve-foot extension rod with a 
nozzle on the end, about twenty-five gallons of the spray being nec- 
essary for a thoro treatment. If these various measures have 
been neglected and the caterpillars have left the tree, they may still 
be disposed of in the pupa stage by digging up and w^orking over 
the ground under the branches and for a little distance outside, to 
a depth of three or four inches. 
Thk White-marked Tussock-moth 
{Hciucrocanipa Icucostigiua S. & A.) 
The most destructive leaf-eater infesting shade trees in the 
larger cities of Illinois and especially in Chicago is the caterpillar of 
the white-marked tussock-moth. It often completely defoliates large 
trees, those most seriously injured being the elm, the soft maple. 
the linden, the birch, and the horse-chestnut. (Fig.)7.) Almost 
every kind of tree, excepting conifers, is subject to its attack, and 
it sometimes becomes decidedly injurious in orchards. In Chi- 
cago it has been noted as injurious to apple, box-elder, hard maple, 
Norway maple, poplar, willow, oak, ash, locust, hickory, catalpa, 
and sycamore, and to several shrubs, including dogwood, button- 
bush. Viburnum, and bladdernut (Ptclea). In September and 
October, 1910, it was found in every one of eighteen towns visited 
by Mr. John J. Davis, present in small numbers in seven of them, 
common in nine, and in destructive numbers in two. 
This is a well-marked insect, very easily recognized, especially 
the caterpillar and the egg mass — the two conditions against which 
measures of destruction must be taken. The hairy caterpillar (Fig. 
8), bright yellow in general color and striped with black, and about 
an inch and a half long when full grown, is a really beautiful object. 
It mav be known by its coral-red head, by two plumelike tufts of 
long black hairs projecting upward and forward from the back near 
the head, by a single similar tuft at the hind end of the body, and 
especially by four thick, short, brushlike clusters of cream-colored 
hairs arranged, one behind the other, in front of the center of the 
back. In this condition it may be found upon infested trees in 
June, July, and August. 
There are two generations of the caterpillar in a year in north- 
ern Illinois, possibly three farther south. The egg masses (Fig. 9) 
from which the caterpillars hatch may be found in fall, winter, and 
early spring. They form, when first deposited, frothy, oval, snowy 
