44 NEW YORK STATE MUSEUM 



insect is thinly covered with short, light buif or yellowish brown 

 hairs and has a length of a little over half an inch. This egg mass 

 is almost invariably deposited upon a filmy cocoon nearly one and 

 one-quarter inches long and one-half inch in diameter and with 

 moderately long, yellowish gray, barbed hairs entangled in the 

 open web. The individual eggs of the definite marked tussock 

 moth have a diameter of about one-sixteenth of an inch, are sub- 

 globular, the darker micropyle being in a marked depression and 

 surrounded by a light yellowish brown, elevated ring, this in 

 turn variably bordered by dark brown shading into pearly white. 

 The micropyle of this species differs from that of the- gipsy moth 

 egg, in that there are usually but seven or eight rather stout, 

 pyriform plates surrounded by a granular area (plate 9, figure i). 



The young gipsy moth caterpillar is slightly over one-tenth of 

 an inch long just after it emerges from the egg. It has a black 

 head and the brownish yellow body is well clothed with long 

 hairs. There is a prominent hairy tubercle on either side of 

 the segment next the head, which gives the caterpillar a peculiar, 

 broad-headed appearance in its earl}^ stages. At this stage we 

 find the peculiar aerostatic hairs, easily recognized by the bulb- 

 like enlargement near the middle (plate 9, figure 6). The other 

 hairs are distinctly barbed (plate 9, figure 5). The markings 

 become plainer as the caterpillar increases in size. 



The full-grown caterpillar is from two to two and one-half 

 inches long and has a double row of conspicuous warts or tuber- 

 cles down its back. The eight anterior, not counting the four 

 blue ones just behind the head, blue ; the twelve remaining, red. 

 Similar tubercles occur on the side. The caterpillar of this 

 species has large, coarse, yellowish and brown or black hairs, 

 both minutely serrate (plate 9, figures 3, 5) and numerous finer, 

 smaller, lighter hairs with minute reticulations on the surface. 

 The full-grown caterpillars, like those of the well-known forest 

 tent caterpillars, assemble in the day on the shady side of the 

 trunks and under side, of the limbs, sometimes forming clusters 

 covering considerable areas. 



The somewhat conical, dark brown pupa ranges from three- 

 quarters to one and one-half inches long and is usually found in 

 numbers lying among a few threads and securely attached to 

 them by its terminal spine. The abdominal segments of the 

 pupa are ornamented with symmetrically arranged, sparse clus- 

 ters of short, yellowish hairs. Similar hairs also occur upon the 

 thorax and at the anterior extremity of the pupa. A microscopic 



