ificity regarding which orchid bees visit which types of orchid. The early description of this pollination system was by Charles Darwin, though at the time, he believed the bees were females. Not all orchids utilize euglossines as pollen vectors, of course; among the other types of insects exploited are other types of bees, wasps, flies, ants, and moths.
Digger Bees. The Anthophorini is a large tribe in the family Apidae, with over 750 species worldwide that were previously classified in the family Anthophoridae; the vast majority of species are in the genera Amegilla and Anthophora. All species are solitary, though many nest in large aggregations. Nearly all species make nests in the soil, either in banks or in flat ground; the larvae develop in cells with waterproof linings and do not spin cocoons. Species in this tribe are often referred to as "digger bees", though this common name is sometimes applied to members of the tribe Centridini, as well (Figure 48).
Digger Bee, Image Courtesy of entomart.
The characters used to define this group are subtle, but they are nonetheless fairly recognizable; they are generally large (up to 3 cm), very robust, hairy bees, with visibly protruding faces, and the apical portion of the wings are studded with microscopic papillae. The abdomen is often banded, and in many Old World species of Amegilla these bands are metallic blue. The wings often appear disproportionately short compared to other bees, and their "buzz" is often a high-pitched whine, as they hover and feed on flowers. Males commonly have pale white or yellow facial markings, and/or peculiarly modified leg armature and hairs.
Attracting Digger Bees. Some digger bees nest in cracks or cavities in soft sandstone and dry exposed soil embankments. Some of these species will excavate tunnels in cliff sides by wetting the hard soil surface with water or nectar to soften it.
To attract these species, adobe bricks can serve as the equivalent of a wooden nest block. Such bricks can sometimes be purchased, in which case you c