Published online by Cambridge University Press: 31 May 2012
The surface features and the fine structure of the chorion of the bumblebee egg are described. The egg is covered by a reticulum of polygonal cells with elevated walls and with variously shaped protuberances at the wall junctions, except at each pole where the reticulum evanesces, Differences in the shape, size, and surface sculpturing of the protuberances and in the appearance of the walls are species-specific and a key to the eggs of the nine species is provided. The very thin chorion is composed of two parts with a third part comprising the walls of the polygonal cells; the egg possesses no aeropylar openings and micropylar openings were not found.