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Indiana University Studies 



males. It is difficult to obtain complete data on the ratio of 

 the sexes, for the males appear to emerge regularly somewhat 

 earlier than the majority of the females (see xerophila, 

 tvasatchensis, calif ornica, riibriderma, and descansonis) . If 

 the galls are collected too early it appears to reduce the num- 

 ber of females emerging, probably by serving to kill the indi- 

 viduals less developed at the time of collecting. All of the 

 galls collected after emergence had proceeded to some degree 

 gave a reduced number of males. It is probably safe to 

 assume that the sexes occur in about equal numbers. 



With the sexes so nearly equal, fertilization probably oc- 

 curs regularly. Whether parthenogenetic development ever 

 occurs would be a matter of interest in connection with the 

 regularly or at least usually parthenogenetic development of 

 some species of the same genus (see Kinsey, 1920, Bull. Amer. 

 Mus. Nat. Hist., XLII, p. 393). No species in the genus is 

 known to exhibit an alternation of generations, and the field 

 data for this species would not suggest the occurrence of that 

 phenomenon. The insects overwinter as larvse, pupating only 

 a very short time before emergence, emerging as adults in 

 early spring, mostly before February 23 on the southern boun- 

 dary of California, to April 22 and later at the higher eleva- 

 tions in Colorado, and July 27 in southern Montana, (accord- 

 ing to Ashmead, for variety similis) . New galls probably 

 begin development about a month after the emergence and 

 oviposition of the insects. This biologic data is remarkably 

 uniform for all varieties of the species, differing merely in 

 dates of emergence as affected by the earlier or later arrival 

 of spring at more southern or more northern localities. 



While red is the normal color of the female, several of the 

 varieties have some of the females black. The heredity prob- 

 lems involved here deserve further study. See our data under 

 variety coloradensis form siihcoloradensis. 



Inquiline-inhabited galls of this species present a consid- 

 erable modification which has resulted in their consideration 

 as distinct species. This is discussed at the end of the paper. 



Diplolepis tuberculatrix (Cockerell) 



FEMALE. — Rufous or black; thorax finely, irregularly roughened; 

 parapsidal grooves continuous; median groove usually evident; scutellum 

 without foveas; radial area only slightly shaded. HEAD: As wide as 

 the thoraxj not broadened behind the eyes; very finely rugose on the 



