Leaf-cutter & Mason Bees (Megachilidae)
Male leaf-cutter bee on blanketflower.
This is an interesting group of bees in that they collect pollen on specialized hairs underneath their abdomen, instead of on their legs. Females will "bump their butt" up and down on flowers in order to get pollen to stick to the hairs under their abdomen. When building nests females collect materials like leaves, flower petals, plant or animal hairs, resin or mud. They use these materials to line the walls of each cell, or to separate cells in the nest, which can be a premade cavity in wood, hollow plant stems, crevises under bark or rocks, exposed rock, or like a few species, dug in the ground.
Roughly 75 species make up the Megachilidae family in Florida, and a large percentage of those bees are in the Megachile genus. These bees are referred to as leaf-cutter bees because the females cut small, almost perfectly round, pieces of leaves that they use to line the inside of their nests with. Many gardeners may have noticed this happening to the leaves of their roses or redbuds and thought that some insect was attacking the plant, but this really means they have leaf-cutter bees nesting nearby. The plants can usually tolerate the loss and don't suffer much damage in the long run. The female uses the pieces of leaves to line the inside of their nest, which helps protect the nest from moisture. Most of these bees nest in premade cavities in wood, like beetle holes, but a few species dig their nests in the ground. If you were to find the nest of a leaf-cutter bee, it would look like a green, leafy cigar. The Megachile spp. in this area of Florida emerge from their nests in spring and can be seen flying until late fall.
Roughly 75 species make up the Megachilidae family in Florida, and a large percentage of those bees are in the Megachile genus. These bees are referred to as leaf-cutter bees because the females cut small, almost perfectly round, pieces of leaves that they use to line the inside of their nests with. Many gardeners may have noticed this happening to the leaves of their roses or redbuds and thought that some insect was attacking the plant, but this really means they have leaf-cutter bees nesting nearby. The plants can usually tolerate the loss and don't suffer much damage in the long run. The female uses the pieces of leaves to line the inside of their nest, which helps protect the nest from moisture. Most of these bees nest in premade cavities in wood, like beetle holes, but a few species dig their nests in the ground. If you were to find the nest of a leaf-cutter bee, it would look like a green, leafy cigar. The Megachile spp. in this area of Florida emerge from their nests in spring and can be seen flying until late fall.
A pair of metallic blue mason bees mating on yellow thistle.
Another group of bees in this family, although not as specious as the Megachile spp., are the mason bees, Osmia spp. These bees emerge from their nests in early spring, but have a short season, roughly March to May. Many mason bees use mud to separate the cells in their nest, but the species seen to the right, Osmia chalybea, uses chewed leaves to separate cells and to seal the nest (Rozen and Hall, 2011). Most of the species in Florida are metallic blue, but in other parts of the country it varies and some are dark or bright metallic green, or even black.
The other large group of Florida's Megachilids are in the genus Coelioxys. These bees are clepto-parasites, otherwise known as cuckoo bees, on bees in the genus Megachile. These bees don't have to collect nectar or pollen, they just have to find nests of their host species. Because of this, they don't have much hair on their bodies, and they have very tapered abdomens, which gives them a more sinister look. Other less common bees in the Megachilidae family include those in the genus Lithurgus, Anthidiellum, Anthidium, Dianthidium, Stelis (another cuckoo bee), Trachusa, Heriades, Hoplitis, and Ashmeadiella.
A beautiful cuckoo bee (Stelis louisae) on Spanish needles (Bidens alba).
Floral Resources for Leaf-cutter and Mason Bees
Turkey tangle fogfruit.
These bees visit many different plant types throughout the season. Here is a list of the most common plants these bees were collected on during the 2011 sampling season at GTMNERR.
- Turkey tangle fogfruit (Phyla nodiflora)
- Dune sunflower (Helianthus debilis)
- Blanketflower (Gaillardia pulchella)
- Yellow thistle (Cirsium horridulum)
- Spanish needles (Bidens alba)
- Eastern milkpea (Galactia volubilis)
- Canadian germander (Teucrium canadense)
