Page:The Gall Wasp Genus Cynips.pdf/42

body color from entirely yellow-rufous in the smaller specimens to darker rufous with some black in the larger specimens. These larger individuals bear a striking resemblance in their wing venation (as far as it is present), body proportions, and much of their color to the still larger insects which are anceps (fig. 337). It is my suggestion that bifurca is the result of recent mutation or mutations which have hybridized with the parental anceps stocks. If the wing characters are actually controlled by multiple factors, we should expect the hybrids to form this sort of graded series. The occurrence of the colonies of bifurca well within the heart of the range of anceps, and the limited extent of these colonies seem indicators of their comparatively recent origins. Bifurca may be an instance of present-day mutation of the sort which, in the past, has given rise to the 42 short-winged species of Cynips.