OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 29 
THE WHITE-MARKED TUSSOCK-MOTH. 
(Orgyia leucostigma Smith & Abbot.) 
HABITS AND NATURAL HISTORY. 
The Eggs.—During the month of June, and more especially late in fall 
and througbout the winter, glistening white objects may be seen on the 
trunks and the larger branches of trees, or in the corners of the fences 
near by, or on bunches of dead leaves hanging on the tree (see Fig. 
13 a). Upon examination these masses will be found to be glued on to 
a cocoon of dirty gray color, and to consist of numerous perfectly round, 
eream-white eggs, which are partly covered by a glistening-white froth 
Fic. 13.—Orgyia leucostigma: a, female on cocoon. b. larva, ¢, temale pupa; @, male pupa. 
or spittle-like matter. In one of these egg-masses which we received 
from Kansas we have counted as many as 786 eggs, while from another 
mass we obtained upward of 400 young caterpillars. 
Development and Characters of the Larva.—tIn the latitude ot Saint 
Louis, Mo., and Washington the eggs begin to hatch about the middle 
of May, and the newly-born caterpillar, not quite 3 millimeters in length, 
is of dull whitish-gray color, with the under side paler, the upper side 
being covered with rather long hairs and tufts of a dark-brown color. 
In two days from hatching small orange spots begin to appear along 
Fic. 14.—Orgyia leucostigma: female caterpillar 
the back, and on the seventh day the first molt takes place, to be fol- 
lowed at intervals of six days each by the second and third molts. 
The changes that take place during this time in the appearance of the 
caterpillar are remarkable, and after the third molt it is a beautiful ob- 
ject and of striking appearance (Fig. 14). The head and two little ele. . 
vated spots situated on joints 9 and 10, are bright vermilion red; the 
