The Seasonal Size Increase of Bumblebee Workers (Hymenoptera: Bombus)

Abstract

Six field colonies and four laboratory colonies of bumblebees were used in a marking experiment during the summer of 1964 in Wisconsin to study the seasonal size increase of the workers. Mean sizes of weekly age groups differed significantly. The workers gradually increased in size in healthy colonies. In colonies disrupted by parasitism or transfer from the field to the laboratory, consecutive age groups of workers were- significantly smaller. After a period of adjustment, the colonies transferred from the field to the laboratory resumed the normal pattern of worker size increase.