1893.] ±i O [Packard. 



of Lepidoptera, except in the hairy Noctuina or Noctuo bombyces, or 

 Bombycoidea. where the hairs with flattened ends probably occur in the 

 more hairy and penciled species. In the larva of the common American 

 Acronycta JiastuUfera, many of the barbed hairs forming the black pen- 

 cils are flattened at the end and black, but not striated. 



Fig. 20. — Flattened setfe of various shapes, usually pointed, a, a small 

 one ; 6, its barbed base ; c, portions of the white barbed hairs ; <X, one 

 blunt and notched at the end ; all X i in. obj., and from tuft on the third 

 thoracic segment of A. hastuUfera. 



These specialized and highly diff'erentiated setae, so like the scales of 

 adult Lepidoptera, appear to be of use in rendering the pencils and tufts 

 more conspicuous and stiff". The shortest and broadest, striated, scale like 

 setse occur on the low, broad, stout, dorsal median tubercles of Gastro- 

 pacha ; and, perhaps, add a repellant nature to these shiny dark metallic 

 tufis. At all events the occurrence of such scales is an interesting exam- 

 ple of the acceleration of development of the setne in these larval forms, 

 and it is not improbable that in the ancestors of the L isiocampidas they 

 were characters acquired during the later stages of their larval lifetime. 



Partial Life History of Clisiocampa thoracica (Stretch). 



Specimens in the third (?) stage were mailed April 28 from California 

 by Mr. L. E. Ricksecker, and received and described May 5. It was 

 feeding on willow leaves, but will eat sparingly of the eastern wild 

 cherry. It has the same habits as the eastern C. sylvatica, spinning a 

 web and living in clusters. 



Larva, Stage 111(1). — Length, 10-13 mm. In this stage it closely resem- 

 bles G. sylvatica when next to the last molt, both in the shape and color of 

 the exclamation-point-like pale dorsal spots ; in having on each side an 

 ochre-brown subdorsal line, though it is more broken, and a distinct, 

 broad, lateral line, which is edged above and below with black. Below 

 this line, low down on the sides of the body, are two whitish, reddish- 

 yellow, wavy, irregular thread-lines, the lower one a little more distinct 

 and pale tawny. The upper of these two lines is present in C. sylvatica 

 (but the lower one is not present in Bridgham's drawing). The space 

 between these two lines is somewhat livid, with pale blue and black dots. 



The head is pale blue, with fine black dots, which are thickest on each 

 side of the median line, and in the middle of each side. The prothoracic 

 segment is bluish, with a median black hair-line, with two converging, 

 lateral, black patches in front, and two shorter ones behind. The hairs 

 on the body are deep tawny, those on the sides, low down, mixed with 

 gray hairs. 



Stage IV{1). — Length, 20 mm. Molted aboat May 10, observed from 

 May 11 to 16. The marks and spots, especially the blue ones, are much 

 more distinct than before. The black dots on the head are arranged more 

 regularly than before, forming a triangular area on the vertex and 



FROG. AMER. PHILOS. SOC. XXXI. 141. W. PRINTED MAY 10, 1893. 



