THE SPRUCE BUD-WORM. 837 



oval cylindrical, a little longer than broad, and in all those which I ex- 

 amined, both those containing the embryos and those which were empty, 

 the surface, contrary to Professor Feruald's statement, was under a lens 

 seen to be finely but irregularly granulated. The shell is thin, and at 

 first unusually soft. Length, 0.9 to 1.4'""'; breadth, 0.8 to 1'"'". The 

 patches were about 3'"'" in diameter, and composed of as many as thirty 

 eggs. The eggs overlapped each other irregularly, leaving about a 

 third or fourth of the surface of each egg exposed. 



From the form and size of the egg-mass it is evidently attached by the 

 moth to a terminal twig. The caterpillars on hatching, as Fernald ob- 

 serves, do not eat the shell. They hatch about or soon after the middle 

 of July, and it is most probable that the caterpillars become partly, per- 

 haps almost wholly, grown before the end of autumn, and pass the winter 

 among the terminal shoots of the tree, to finish their transformations the 

 following June and July. It is certain that there is but a single brood of 

 caterpillars. Professor Fernald, in his article in the American i^aturalist, 

 describes the process of egg-laying. He has bred from the worms an 

 ichneumon {Pimpla conquisitor), several dipterous parasites and a hair- 

 snake. We have found the insect to be remarkably free from parasites, 

 having bred about twenty-five of the moths without rearing any para- 

 sites. 



Larva, first stage. — When first hatched the youngj caterpillar is uniformly pale pea- 

 green, with a yellowish tint. Head dark brown, but the cervical shield pale amber, 

 with two dark dots on the hinder edge ; hairs nearly half as long as the body is thick ; 

 length 2.5™™. At this time the youug worms are very active, letting themselves 

 down by a thread as readily as when fully grown. 



Larva: hefore last molt. — Body not quite so thick as full-fed worm ; more uniformly 

 rust-red brown; the piliferous warts duller in color, sometimes not much paler than 

 the rest of the body towards the head, though higher and more distinct towards the 

 end of the body. Head black and prothoracic shield black, the latter pale on front 

 margin ; no well-marked, broad, lateral, yellowish-brown band such as characterizes 

 the adult. Length 12 to 13""". 



Larva {full-fed).— BoAj unusually thick and stout, tapering gradually from the 

 middle to the end, and slightly flattened from above, as usual ; head not quite so wide 

 as the body, of the usual form, dark, almost black-brown, but lighter than before the 

 last molt; mouth-parts dark, with paler membranous rings at the articulations; 

 anteunte with the terminal joint black. 



Prothoracic shield pale brown, paler than the body, with a pair of dark blotches on 

 the hinder edge in the middle, and other scattered, smaller, dark, irregular blotches, 

 of which two are situated in the middle of the front edge, the latter pale whitish. 

 Body rich umber-brown, diffused with olive-green, especially on the sutures; with 

 very conspicuous and showy, large, whitish-yellow, piliferous warts, forming flat- 

 tened minute tubercles, with a dark center from which the hair arises. On the top 

 of the second and third thoracic segments is a transverse row of four such warts on 

 each segment ; on the upper side of the abdominal segments are four warts arranged 

 in a short trapezoid ; they are far apart transversely, but unusually near together 

 antero-posterior to the body ; on the penultimate segment is a median, broad, lio-ht- 

 yellowish spot on the hinder edge of the segment; a large, round, convex area, form- 

 ing the supra-anal plate, from which arise about sis fiue, long, pale-brown hairs. 

 Anal legs spreading, with two or three piliferous callosities ; the terminal segment and 

 anal legs coucolorous, with an irregular, broad, pale-yellowish, lateral band reaching 



