lO NEW YORK STATE MUSEUM 



The young caterpillar is slightly over yV inch long just after it 

 emerges from the egg. It has a black head, the body is brownish 

 yellow and 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 

 early stages. The markings become plainer as it increases in size 

 and when full grown it is from 2 to 2 J inches long. The caterpillar 

 then has a double row of conspicuous warts or tubercles down its 

 back, the eight anterior, not counting the four blue ones just behind 

 the head blue, the 12 remaining red. Similar tubercles occur on 

 the side. Two nearly full grown caterpillars are represented on 

 plate I, figures 6, 7. These caterpillars, like the well known forest 

 tent caterpillar, Malacosoma disstria Hiibn., assemble 

 in masses on the trunks [pi. 5] and underside of limbs, sometimes 

 covering large areas. 



The somewhat conical, dark brown pupa [pi. i, fig. 5], ranges 

 from I to I J inches long and is usually found in numbers [pi. 6] lying 

 among a few threads and securely attached to them by its terminal 

 spine. 



The male and female moths differ widely. The former is a 

 slender, olive-brown, black marked insect with featherlike antennae 

 and has a wing spread of about i J inches. It is represented with 

 wings expanded at figure 3 and in a resting position at figure 4 on 

 plate I. It flies in the late afternoon and early evening. The 

 female is much heavier and ligher colored. She has a wing spread 

 of about 2 inches and is white or buff -white with more or less dis- 

 tinct black markings. The abdomen is tipped with black. She is 

 represented with the wings spread and in the characteristic resting 

 position at figures i and 2 respectively, on plate i and on plate 7. 

 The female moth does not fly though she apparently has well 

 developed wings. 



History in America. This pest was introduced into Medford, 

 Mass. in 1868 or 1869 and, escaping from its introducer, attracted 

 little notice for about 10 years. Then the caterpillers became 

 somewhat abundant and in 1889 Medford and vicinity were liter- 

 ally overrun with the pests, the infestation bordering closely on a 

 plague. An act, passed in the winter of 1890, provided for the 

 appointment of a special commission and placed at its disposal 

 $25,000, which sum was subsequently increased by an equal amount. 

 An appropriation of $50,000 was made in 1891 and from then to 1899, 

 appropriations ranged from $75,000 to $190,000 annually. The 

 total amount expended by the commonwealth of Massachusetts 



