Measurement and estimation of functional proboscis length in bumblebees (Hymenoptera: Apidae)

Abstract

Analysis of a 16-mm cinefilm of feeding bumblebees (Bombus) indicated that the glossa is the functional unit of proboscis length. This was corroborated by observations of the depth to which wild bees probed Impatiens biflora and by data presented in the literature. Accurate measurement of the glossa length of bees that died with their proboscides folded is facilitated by straightening the labium by dissection. Regression equations describing the relation between glossa and wing length, derived from bees from a single colony, provide sufficient accuracy to allow prediction of glossa length for that species in a field study.