Brood-Rearing in Relation to Worker Number in the Ant Myrmica

Abstract

winter into a characteristic quantitative as well as qualitative composition. The number of final-instar larvae was roughly proportional to the number of workers, and larvae were bigger when workers were relatively numerous. Evidence was thus provided in support of the hypothesis that the growth of the worker population was autocatalytic, the numbers at any time playing a large part in determining the amount of growing juvenile replacement material. To understand how this regulation is achieved would necessitate full analysis of the social processes involved, but as a first step it is clearly desirable to discover by experiment how worker group size affects brood growth in general, and it is with this that the present paper is concerned. The results of the culture of fixed quantities of brood (starting either as eggs or as larvae) by variable numbers of workers are presented. In addition to this preliminary analysis of the social regulatory mechanism, some light has been thrown on the question of the social conditions relating to the production of queens and workers. Wesson (1940) has shown, using species of the Myrmecine ant Leptothorax, that, after hibernation, amply fed cultures