July 9,1917 Study of Eriosoma pyricola 71 



The mature wingless female of the second generation is oval, dark 

 bluish black, the body clothed with short white waxy threads (longest 

 at the caudal extremity) and pruinose "meal" of the same color; the 

 cornicles are black and very short; the antennae are one-third the body 

 in length; the antennae and legs are bluish gray with a lilac tint, although 

 at first pale orange; the tibae and base of the femora are paler than the 

 rest of legs. 



The wingless forms matuire in about three weeks inside the gall. In 

 1 91 6 they were not at all common, as will be seen from the records 

 which follow. They are the earliest progeny of the stem mother and 

 apparently deposit young destined to acquire wings, as no third-genera- 

 tion wingless forms were ever found. Isolated individuals, when placed 

 in empty galls, failed to deposit young or to remain where placed for 

 more than a very few days. At the time the first wingless forms ma- 

 tured, pupae occurred in the galls, and the latter must have been direct 

 progeny of the stem mothers. 



To indicate the scarcity of these second-generation wingless forms, a 

 few observations may be cited: 



^ On June 6 two galls were selected at random for examination of the 

 inmates. One contained, besides the fundatrix, 6 adult wingless forms, 

 29 pupae, and 250 larvae; a second contained, besides 3 fundatrices, 31 

 adult wingless forms, 71 pupae, and 531 larvae. On July 24 a gall con- 

 tained 6 dead wingless forms, 6 dead pupae, and 63 pupal skins. During 

 the next two weeks 3 other galls were examined without any trace of 

 second-generation wingless forms being discovered. It might also be 

 said that among the larvae found in the first two galls there were very 

 few individuals of the size and shape of a wingless form of the fourth 

 instar. The possibility of the second generation's wingless forms leaving 

 the parent gall and founding new galls should not be overlooked; yet 

 the observations made indicate either that no such movement exists or 

 that it is uncommon. Every gall examined about a month after the 

 stem mother matured contained a small number of these wingless second 

 generation individuals, but their production appeared to be limited to 

 just a few of her earliest progeny. 



The pupae of the spring migrant are at first pink, and, when ready to 

 transform, lilac, with the thoracic region suffused with light yellow. The 

 appendages are light amber, and the wing pads pale yellowish white. 

 They are clothed with woolly and waxy filaments, the latter arising from 

 four longitudinal rows of dorsal and dorsolateral pores. The pupae trans- 

 form within the gall into winged parthenogenetic forms. 



The spring migrants newly transformed are rich brown and soon 

 change to their permanent dark greenish or brownish black color. The 

 shape is elongate, and the body is shining. The general resemblance to 

 the fall migrant is very marked. The head and thorax are shining black ; 

 the prothorax and abdomen vary from deep lilac to dark green, 

 98973°— 17 2 



