The two known species of Megastigmus from rose hips afford an unusually favorable group for study of intraspecific and interspecific variation in size and color of the adults. They are very closely related (Milliron,1949, p.293), and have very similar habits and development, yet show striking differences as to the range of variation in size and color and also the numerical ratios of the sexes. The American form, Megastigmus nigrovariegatus Ashmead, and particularly the male, varies extremely in the percents of dark color, i.e., brown to black versus yellow pigmented areas on the body, and apparently comprises equal numbers of males and females. By contrast, the European species, M. aculeatus (Swederus), now known to occur also in Japan, China and the United States of America, shows, in my reared series, comparatively little range in color and size, and is predominantly female.
Balduf, W. V., "Variations in Megastigmus from Rose Hips (Torymidae, Hymenoptera)" (1957). An. Paper 274.
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