ID GUIDE TO WILD BEES - NEW YORK

Thoracic Cellophane Bee - Colletes thoracicus -(c) Copyright 2017 Paula Sharpman Photo

RESIN BEES

CELLOPHANE BEES: Bees of the genus Heriades line the cells of their nests with a waterproof material which, when dry, resembles clear plastic. Accordingly, they are sometimes called “cellophane bees” or, alternately, “polyester bees”. Cellophane bees are equipped with unusual forked tongues, which they use to paint the plastic-like material onto their nest walls in order to keep their nests dry. The bees produce the material from a special abdominal organ called the Dufour’s gland, named after French naturalist Léon Jean Marie Dufour, who first recorded his fascination with the bees’ fabrication of plastique in 1835.

According to the Xerces Society's Guide to Attracting Native Pollinators, cellophane bees also spray their egg-cell walls with a natural fungicide and bacteriacide, linalool, secreted from a gland in the bees' mandibles. After coating their cells, the bees fasten their eggs onto the cell walls rather than leaving them on nest floors where moisture might collect. The bees provision their cells by mixing pollen and nectar together to make a liquid “bee bread” for their offspring; these provisions are stored in cellophane sacs that look a little like elongated plastic sandwich bags. The special measures taken by the bees to protect their eggs against water and fungus allow them to build nests near stream banks and other areas with wet soils.

Cellophane bees are solitary. They construct individual nests in the ground, excavating tunnels that exit through small round holes. Despite their solitary status, the bees tend to build their nests near one another. Groups of nesting cellophane bees sometimes number into the tens of thousands. These bees, however, are non-aggressive and do not form swarms. They are important pollinators of spring trees, crops and wildflowers.

Heriades carinata Resin Bee

Heriades carinata

1/6" to 1/4" (small)

Heriades variolosa / leavitti Resin Bee

Heriades variloosa / leavitti

1/5" (small)

Heriades are native resin bees equiipped with mandibles designed to scrape resin from plants. These native bees nest in pre-existing holes in wood and hollow stems, and they use plant resin to plug entrances to their egg chambers.

The common name "resin bee" is also applied to other bee genera – for example, resin bees of the genus Megachile are shown on this guide’s leafcutter bee page. Heriades tend to be smaller than resin bees of that genus. The two Heriades resin bees shown here, for example, are a mere 1/6 to 1/4 inch in length.

Like the Osmia and Hoplitis mason bee shown in this guide's preceding section, Heriades belong to the tribe Osmiini of the family Megachilidae. Females carry pollen on scopal hairs under their abdomens; and the bees' forewings have only two submarginal cells.

According to entomologist Charles D. Michener, defining traits of bees of the genus Heriades include the following: (1) A ridge runs across the front top edge of the first segment of the bee's abdomen (as shown in the accompanying photo strip); and (2) the front face of the bee's abdomen is concave.

Heriades of several subgenera are found throughout the world, but a single subgenus, Neotrypetes, occurs within North America, ranging from Canada to Panama. Heriades found in the United States are black with pale hair bands. Coarse Indentations pit their heads, thoraxes and abdomens. The scopal hairs on female bees' abdomens are usually white and often long and conspicuous even to the naked eye, despite the bees' small size.

Male Heriades can be recognized by their abdomens, which curl under, the tips nearly touching the front segments. On males, only S1 and S2 (the first two segments of the sternum) are generally visible when the bee is turned over. Viewed from above, the last segment of the male bee's abdomen (T7) is hidden by the sixth segment (T6).

The tip of the male Heriades abdomen lacks notches or teeth, a trait which helps differentiate this genus from similar bees of the tribe Osmiini.

Heriades tend to be generalist pollinators that forage on a range of plants. In our area, they are commonly found on such plants as agastache, allium, butterfly weed, coreopsis, fleabane, goldenrod, marjoram, mountain mint, sumac, swamp milkweed, spreading dogbane, wild bergamot and members of the squash family.

There are at most three or four species of Heriades resin bees in the New York area. The female bee shown here has been identified as belonging to one of two very similar resin bee species -- Heriades leavitti or Heriades variolosa. This resin bee was found foraging on orange butterfly weed (Asclepias tuberosa) in the VIsitor Center garden of Rockefeller State Park Preserve in early July, 2017.

The second bee at right is a Heriades carinata. This bee as a keel-like structure, called a carina, on its mandibles. This trait is diagnostic of the species.

Heriades carinata do not emerge until the weather grows hot. These bees appear in the vegetable and cut-flower fields of Stone Barns Center for Food and Agriculture in August.

Heriades carinata are reported to be energetic pollinators of onions and leeks. The Heriades carinata bee shown here was found feeding on fringed quickweed, a plant of Mexican origin now naturalized in the United States and belonging to the aster family. This naturalized weed self-seeds in Stone Barns' dahlia and strawflower beds.

TAXONOMY - HERIADES RESIN BEE

Family: Megachilidae
Subfamily: Megachilinae

Tribe: Osmiini

Genus: Heriades

Subgenus: Neotrypetes
Species: Heriades carinata