242 



rows but a short time previous. The life history as given by Mr. Jack 

 is as follows : 



On June 10 the first eggs were discovered and within a few days they were quite 

 abundant. The eggs are pale green, oblong, and about four one-hundredths of an 

 inch in length. They are deposited singly within the tissue of the leaf on the upper 

 side. From one or two dozen to three or four hundred eggs may be deposited within 

 a single leaf without any very definite order, although most of them are usually dis- 

 posed in lines parallel with the midrib, or with the principal veins. Each egg makes 

 a little swelling, noticeable on both the upper and the under sides of the leaf, and, 

 with a little practice, egg-bearing leaves may be readily detected. 



On hatching, the larvaB emerge on the under side of the leaf. They are then about 

 six one-hundredths of an inch long and pale green in color, with yellowish head and 

 black eyes. When at rest they keep close together, coiled up on the under side of 

 the leaves ; and they appear to feed only in the cooler parts of the day, in cloudy 

 weather, or perhaps at night. Of the first leaves attacked, they eat only the more 

 tender parts, and the leaves are left somewhat skeletonized ; but as the larvae get 

 older they devour every part of the leaf down to the midrib. After the first molt, 

 when they are about twelve one-hundredths of an iuch long, the larvae secrete a pe- 

 culiar, very white efflorescence, by which the back and sides become covered. This 

 is constant after each molt until the last. 



This efflorescence is removed by the slightest touch, and when brushed off the color 

 of the body is a pale greenish white. The head after the first molt is black, and 

 the legs and under sides of the body yellow. At full growth the average length of 

 the larva is about an inch. Some are smaller than others, however, and this possi- 

 bly indicates the difference of sexes. 



When the larva has cast its skin for the last time a complete and surprising change 

 has taken place. All trace of white is gone, and the body is greenish yellow on the 

 back and yellow beneath and along the sides below*the spiracles. On each segment 

 along the back are two large and two small black spots, and upon the sides, clos6 

 above the spiracles, is a row of nearly square, black spots, one for each segment, but 

 so placed as to lap over from one segment to the next. The terminal plate above the 

 ventral segment is black. The legs and prolegs are yellow, the former having a 

 reddish spot on the outer side near the base. The tips of the claws arc black. The 

 great change produced by the last molt has led some observers to suppose that there 

 are two distinct species. 



Full growth is attained by most of the larvae early in August, but some may not 

 reach maturity until much later, and this season a few were noticed to pass the last 

 molt about September 20. The season last year was not so advanced, and, in some 

 places, large numbers of larvae were found in September. The larvae eat very little 

 after the last molt, and very soon they leave the plant and wander away in search 

 of suitable places in which to hibernate. Stray pieces of decaying wood, fence posts 

 and rails, dead branches and the corky bark of old trees are selected. In the Arbor- 

 etum, many were found even boring into the soft pith of dead stems of elder bushes. 

 Sometimes two or more occupy one burrow. It is quite possible that some larvae go 

 into the ground to hibernate, but none have been discovered there. 



Figures of the larvae, showing characteristic position on leaves, and 

 also the nature of their hibernating burrows in decaying wood, are re- 

 produced from Mr. Faxon's figures. 



We had identified adults as H. (Emphytus) testacens, and after again 

 carefully examining our specimens it seems probable that the species 

 just named and H. varianus are identical. Those obtained from the 

 larvae received from Mr. Crane form a very good connecting series be- 



