Many species of insects are known to have symbiotic microbes. Such symbiotes, especially ectosymbiotes, commonly interface the insect nutritionally and physiologically with some primary energy substrate. Thus, the insect obtains its required nutrition by cultivating symbiotes on wood, and then eating the microbial mass. During the coevolution of such highly specialized symbiosis unusual nutritional requirements might be expected to arise in the insect, microbes or both. Insects per se are unable to synthesize sterols, and thus require dietary sterol. The male adult also depends on the ectosyrabiotes for dietary sterol. The specific role of ecdysteroid-hormone versus tissue-component-sterol "pools" in this sex remains unknown. However, it is known that the basal titer of free ecdysteroids in males seems to be about one-half of that in the diploid female. Contrary to the situation in the fertile female, the titer in males remains fairly constant during the vigorous period of its life.