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@ antdude:
I would be lucky if somebody could resize my too large pictures. Next time I will try to make them smaller - it was my first trial!

@Dr Ant: There is an enormous literature on the phenomenon of gynandromorphism in ants, bees, and other insects. One interesting paper: Berndt, K.-P. & G. Kremer, 1982: Heat-shock induced gynandromorphism in the pharaoh's ant, Monomorium pharaonis (L.), Experientia 38, 798-799. The authors depict a couple of examples. They put small colonies of the ants from the ordinary rearing temperature of 28 degrees C for variable time into 54 C, near the upper limit of temperature tolerance. After an exposure time of between 30 and 110 minutes the ants were brought back to the normal temperature. The colonies then reared between 1.5 and 83 % gynandromorphs (among the new sexuals produced), and between 0 and 14 % "ergatandromorphs" (among the new worker pupae). Ergatandromorphs are workers with a few black spots of male cuticle, and gynandromorphs are specimens with wings, being halfside gynandromorphs or mosaics of male and female structures.
Much more pictures are found in Kremer, G. & K.-P. Berndt (1986): Zur Morphologie normaler und gynandromorpher Pharaoameisen Monomorium pharaonis(L.). Dtsch. ent. Z., N.F. 33, 177-221 (in German). According to the authors the eggs are influenced by the heat shocks both before and after being laid. - Maybe that in some instances (especially half-side gynyndromorphs) the egg has already undergone the first division(s), and only one of the two (or few) cells was hit by a sperm. But mosaics etc. are more difficult to explain. - For me most fascinating is the fact that both male-gyne and male-worker mosaics occur: This must mean that the (external) factors for caste determination act on female tissue but not on male. This fits well to the observation that colonies of several ant species in somehow "bad" years produce workers and males only, and in "better" years gynes in addition: Gyne-destined female larvae can be redetermined to become workers (or intercastes), whereas male larvae even in poor conditions can finish their development into males. It has to be defined what are "bad" or "good" years for the ants, though. The observation, however, has to be taken into consideration in all studies of sex ratios in social hymenopterans. In the European Stenamma debile we found numerical sex ratios of between 255 males/one gyne and 1.69 males/ gyne in three subsequent years. - But this is already OT.
A. Buschinger