How do Inquiline Bees find the Nest of their Host?

Abstract

THE following observation may serve to throw light on the above question, which has doubtless occurred to many entomologists. Yesterday I saw a specimen of the inquiline Coelioxys quadridentata enter the burrow of a leaf-cutter bec, Megachile circumcincta. I dug the nest out of the burrow; and in so doing scattered the sand over an area of several square inches, completely destroying all appearance of a burrow. I sat down to await the return of the Megachile, in order to identify the species, and was much astonished to see (and capture) in the course of the next ten minutes two more specimens of Cœlioxys, which came hovering over the spot and alighted on the disturbed soil. I can think of no other explanation than that these “cuckoos” were attracted to the spot by the scent of the excavated nest. I may add that during several hours spent on the heath where this occurred I saw no other specimens of Cœlioxys, and, further, that there was a fresh south-east breeze blowing at the time, and that the bees came up against the wind.