104 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Larva. — Stage /—Length fi-7 mm. Head black, a* wide as the body. Prothoracic plate 

 dark chestnut, almost black. The two horns on the second thoracic seoment black, as well as the 

 conical spines on the abdominal segments 'J and 10. 



At the beginiung of the stage the body is considerably darker than at the end. where it is 

 amber or pale gamboge or of the color of beeswax (PI. IV, lig. 1), with faint traces of two 

 lateral pale, yellowish lines, which are more pronounced in the next stage. 



The two horn-like spines on the second thoracic segment are but little longer than the seg- 

 ment bearing them is wide, or than the maximum thickness of the body. 



The conical dor-sal tubercles on the abdominal segments are moderately high and distinct, 

 and ar-e one-half smaller than those on the thiixl thoracic segment. 



Suranal plate and the triangular area on the outside of the anal legs l)lack. while the rest of 

 the anal legs is pale, greenish _vellow. The suranal plate is cordate. For the shape and arma- 

 ture see PI. LII, tig. 1. 



Stage II. — Length. 7 nan. Head large and full, dark umber, wider than the middle of the 

 bod}-. The prothoracic segment is broad, with the front and sides flaring; upper surface dark 

 chestnut. Body chestnut-amber. From the second thoracic segment two very long, sparsely 

 spinulate, black horns arise, which are nearly half as long as the body; they are a little flattened 

 at the tip, ending in two piliferous tubercles. There are on all the other segments six rows of 

 conical acute black tubercles; the eightli segment is armed exactly as the seventh. All these 

 tubercles are distinctly- larger and more prominent than in Stage 1. On the ninth is a single 

 median spine. The tenth segment, or suranal plate, is paler than the body, and near the edge are 

 six whitish tubercles, and at the end are two long, piliferous tubercles. The spiracles are white, 

 distinct, being ringed with black. The thoracic and middle al)dominal legs are black; the anal 

 legs of the same varnish-colored tint as the suranal plate. The skin of the body is rough, with 

 two lateral ridges, on the upper one of which the spiracles are situated and on the lower a spine. 

 Across each segment behind the spine is a transverse row of small whitish warts, and other 

 granulations are scattered over the body. The caterpillar is dark and a somewhat consi^icuous 

 object on an oak leaf. Received from Providence, R. I.. July 1. It molted about July l-t oi' 1.5. 



In the examples of this stage drawn by I\Ir. Joutel the head is dull raw sienna brown, the 

 prothoracic shield brown, while the second thoracic segment above is, directly after hatching, 

 reddish brown. The two lateral lines (subdorsal and infraspiracular) are pale and faintl}' 

 indicated. The larva diflers from Stage I in the pale-brown head, pale suranal plate and anal 

 legs, and in the broad dusky dorsal band and more distinct lines. 



Stage III. — Length, 1.5 mm. Head light chestnut, slightly narrower than the body, which 

 is now colored somewhat like the full-fed larva, though only the lower pinkish line is clearly indi- 

 cated, the subdorsal pink line being narrow and faint. The two horns on the second thoracic 

 segment are now much shorter in proportion, being one-third longer than the segment is wide, 

 or as long as the second and third thoracic and flrst al)dominal segments taken together. The 

 color of the bodj' is nearly the same, but the white granulations, very unequal in size, are moi'e 

 distinct than before. The spiracles are wholly black, and situated between two indistinct brftkeu 

 white parallel lines. The black dorsal spines on the thii'd thoracic and flrst alxlominal segments 

 are smaller than those on the other abdominal segments; those on the eighth and ninth segments 

 are of the same size and larger than those on the other abdominal segments. The suranal plate 

 and anal legs are pale aml)er, much paler than the rest of the l)ody. The plate has two black 

 conical spines, one on each side. (PI. LII, flg. Xa). It molted July 'I'l., having l)een about seven 

 days in this stage. 



Stage IV. — Length, 21 nun. Head as l)efore, as wide as the body in the middle, but now 

 greenish, as in the last stage. Some new marks now appear; there is a broad, do7'saI, dark, 

 longitudinal hand composed of a series of square dark patches, sprinkled over with thickened 

 white granulations, and a sahdoriial hand of the same color, composed of oblong dark patches, 

 bearing a spine above, and on the lower edge the black spiracle, situated on a white field. The 

 skin is of the color of beeswax; in some specimens decidedly greenish in hue. There is a median 

 black forked spine on the ninth abdominal segment. The suranal plate is as before, but the 



