|Figure 2 - The nest here is in a hole in a brick wall.|
Leafcutter bees (genus Megachile) are aptly named as the females of most species, cut circular pieces from leaves (Figure 1) which they use to build their nests. The nests are usually built in pre-existing holes in wood or other structures (Figure 2), and many species can be encouraged to nest in drilled wooden blocks. The cut leaf pieces are used to construct thimble-shaped structures where pollen and nectar is formed into a ball, upon which an egg is laid.
To cut the leaf pieces, the mandibles (or jaws) of female leafcutter bees have serrated cutting edges, much like a steak knife (Figure 3). However, not all leafcutter bees are “leafcutters”, and many species instead collect plant resins to build their nest. Females of most of the resin-collecting bees do not have the serrated cutting edges on the mandible (Figure 4) – they are not required as the fresh resin is honey-like in consistency, and can be easily collected and shaped by the bee until it hardens.