i66 



that the larvae which pupated with the tufts white would produce 

 females. 



I observed one change in some that pupated September 20 

 that I had not noticed before, Just before they underwent this 

 change the stripes of yellow hairs along the sides became nearly 

 white, but with a greenish tinge. September 10 and 13 I found 

 Orgyia larvse on pear, as also on apple trees, with white as 

 well as yellow tufts, and one in which the yellow stripes had be- 

 come greenish-white. The caterpillars found September 2 all 

 produced females. There was a difference in size as well as 

 in markings among the males obtained, some being larger than 

 others ; some with no light spot on the wings, and some much 

 lighter-colored than others. 



I found the larvse still feeding on apple trees as late as Octo- 

 ber 8. A pupa found October 4 was full of eggs, showing that 

 the eggs develop pretty soon after the caterpillar goes into the 

 pupa state. 



In November I put some eggs in a box to be ready for further 

 experiment. May 19, 1879, these eggs hatched and the little cat- 

 erpillars had blackish heads but with a tinge of red underneath. 

 A cluster of eggs from which I expected to obtain Orgyia an- 

 tiqiia did not hatch. The larvae of O. leucostigma were found 

 feeding in orchards by May 20. Of those hatched in the box 

 some had lost their yellow tufts by June 3, and I observed that 

 those with white tufts had darker-colored bodies than the others. 

 I again separated the white tufted ones from the others, but soon 

 found both colors in the boxes, but the white ones had their heads 

 as well as the warts on their backs orange-colored. June 6 I ob- 

 served the most singular feature of all thus far noticed. One of 

 the caterpillars had all the hairs on the back of a beautiful velvety 

 black. 



The Orgyia that hatched May 19 pupated June 17, and pro- 

 duced the imago June 29, showing quite a variation in the time 

 these caterpillars remain in the pupa state. Some came out males, 

 some females, showing that sex could not be determined by the, 

 color of the tufts. 



June 22 the larva with the black tufts came out white, and 

 the 23d it changed again to yellow. It pupated the 30th, and in 

 due time produced a female. 



September 6 I found several fawn-colored Orgyia on a hazel 

 bush, but did not succeed in rearing them. The tufts on the back 

 were darker-colored than the rest of the hairs. After all my ob- 

 servations, I have nearly come to the conclusion that O. leucos- 

 tigma and O. antiqiia are only forms of the same species. I know 

 not positively, and shall make farther observations the coming 

 summer. I have learned that it is not safe to draw hasty conclu- 

 sions if I have learned nothing- else. 



