Larval recognition by workers of the ant Myrmica

Larvae are indistinguishable from pharate pupae, and both arouse more worker response than either pupae, or flaccid or shaven larvae. Larval skins elicit a normal response, and masking shows that a surface signal is widely dispersed. The reactive substance is insoluble in hexane, water, methanol, and 70 per cent ethanol, but soluble in acetone, ether and chloroform. It resists 100 °C for 10 min or more. Workers can distinguish diapause-developed from worker-biased brood in spring, not because of their size, their growth rate, or their queen-potentiality, but because they emit a special signal from the ventral surface. This signal is not species specific though the basic larval recognition signal is, at least between Myrmica rubra and Myrmica scabrinodis.