July 1S91.] 



PSYCHE. 



Ill 



Orgyia definita Packard. 



1864. Packard, Proc. ent. soc. Phil., 3, 



332- 



18SS. Lintner, 4th rept. N. Y. state en- 

 tom., p. 50. 



1891. Thaxter, Can. ent., 23, 34. 

 This species has six stages in larvae that 

 produce male moths, and seven stages for 

 female moths. I have observed all but the 

 first of these stages, and the life history, as 

 far as I have made it out, is as follows : — 



Egg. Nearly spherical, the top a little 

 flattened; a large, central, brownish spot 

 with a paler dot at the apex of the egg, sur- 

 rounded by a concentric concolorous ring; 

 diameter 1 mm. The eggs are laid in masses 

 on the cocoon of the female moth, but are 

 not naked as in the O. nova, nor covered 

 with froth as in O. leucostigma, but with the 

 hairs from the body of the moth, which are 

 rubbed on by the female before it dies. The 

 eggs are gummed together, and the hair also 

 adheres to them. The winter is passed in 

 this stage as with the allied species. 

 First stage. Not observed. 

 Second stage. Head pale whitish, width 0.7 

 mm. Ocelli black, mouth brown. The 

 warts on the body are small, except a large 

 pair on joint 2, which bear two or three short 

 plumed black hairs; a few more of these 

 hairs arise dorsally on joint 12. The other 

 warts bear a few long white hairs. The body 

 is pale whitish, the retractile warts on joints 

 10 and 11 whitish. There are traces of the 

 two anterior of the four dorsal, brush-like 

 tufts which are seen in the mature larva on 

 joints 5-8. Even in this early stage the char- 

 acteristic markings of the mature larva are 

 developed, though somewhat indefinitely. 



Third stage. Head pale yellowish, jaws 

 black; width 1 mm. The warts are arranged 

 as in the mature larva, small, concolorous 

 with the body, the large ones on joint 2 bear, 

 ing thin pencils of plumed black hairs. A 

 similar pencil, mixed with shorter brown 

 hairs, arises from joint 12. The body is pale 

 whitish, with a yellowish subdorsal band on 



the posterior segments and a stigmatal band 

 running the whole length, wider on joints 

 5, 6, and 7. Three dorsal, deep yellow tufts 

 on joints 5, 6, and 7 respectively. The warts 

 bear thin, whitish hairs; the dorsal retractile 

 ones on joints 10 and 11 are whitish with a 

 blackish shade around them. Length of 

 larva 10 mm. 



Fourth stage. Head as before, with a small 

 brown shade above the mouth ; width 1.5 mm. 

 The body differs only in being shaded with 

 blackish dorsally and laterally. The yellow 

 tufts are now four in number on joints 5-8. 

 The cervical shield is pale yellow like the 

 head. 



Fifth stage. Width of head 2.1 mm. Be- 

 tween the yellow dorsal tufts are a series of 

 velvety black spots, concealed unless the in- 

 sect is disturbed. The dorsum is gray, 

 broadly so anteriorly, but partly replaced by 

 a yellow subdorsal band on joints 9-13. The 

 lateral region is gray, the warts whitish and 

 partly surrounded by yellow. A narrow 

 stigmatal band. Otherwise as before. 



Sixth stage {$ mature larva). Head pale 

 yellow, shiny, the labrum and antennae 

 white; width 2.8 mm. Body pale yellow, a 

 pale, almost colorless, dorsal band, replaced 

 on joint 2 by the pale yellow cervical shield 

 containing two darker yellow warts, narrow 

 and greenish on joints 3 and 4. widening and 

 enclosing the yellow dorsal brush-like tufts 

 on joints 5-8, narrowed on joints 9-12 en- 

 closing the concolorous retractile tubercles, 

 and absent on joint 13. A narrow subdorsal 

 and fainter stigmatal, similarly colored lines. 

 These bands are in some specimens more or 

 less blackish, or black, blue-gray, or dark 

 brown, and there is a velvety black spot be- 

 tween the dorsal tufts on joints 6, 7 and 8. 

 The warts are all pale yellow; the pencils on 

 joint 2 are long, plumed, black; that on joint 

 12 of light brown hair with a few long black 

 plumed ones on its posterior side. The other 

 hair is long, thin and white. 



The larva does not differ structurally from 

 O. leucostigma, but differs markedly in color. 



