Periodicity in the behavior of grain beetle larvae

Larvae of the grain beetle (Tenebrio molitor) were trained in a T-maze at different stages of the same instar. The larvae's aptitude for learning changed depending on the stage of their development: poor in the middle of the intermoulting period, but much improved upon approaching the next moult and during the 1st day thereafter. Such regularity seems to be related to general laws of cyclic development of the insect larvae as governed by the hormones of metamorphosis.