Tribe Osmiini - Genus Heriades
Heriades are referred to in some popular texts as “resin bees”. 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. Heriades are specially equipped with mandibles designed to scrape resins and saps from plants.
Heriades of several subgenera are found throughout the world, but a single subgenus, Neotrypetes, occurs within North America, ranging from Canada to Panama. Approximately 10 Heriades species inhabit the United States, at least 7 of which are found in Texas.
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 variegated Heriades resin bees shown here, for example, are a mere 5-6 mm (less than 1/4 inch) in length.
Physical Characteristics of Heriades Resin Bees
Like the Osmia 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 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, such as Osmia and Ashmeadiella. These features are illustrated in the entry below.
Heriades females of various species are differentiated by minute traits such as the appearance of ridges and protuberances on their jaws, and the density and size of the pits on their upper abdominal segments. Males are told apart by equally minute attributes, such as sculpting and pitting on the sternum; and the length of the vertex (the distance between the small eyes called ocelli and the back of the bee's head).
Heriades tend to be generalist pollinators that forage on a range of plants. The female variegated resin bee featured below was found collecting pollen from the weed known as romerillo (Bidens alba). Heriades variolosa is a common species in all three counties of the Valley. It is most visible during the fall, and often found feeding on small-flowered Asteraceae.
A female variegated Heriades resin bee
TRAITS OF HERIADES RESIN BEES
The heads and bodies of Heriades resin bees are heavily pitted.
Female Heriades resin bees of the United States tend to have pale bands of hair on the upper abdomen and pale pollen-collecting scopal hairs on the sternum.
Close-up of the front of a female Heriades abdomen: the front edge of the first abdominal segment (T1) is ridged.
TAXONOMY OF HERIADES RESIN BEES
Species shown on this page:
Heriades (Neotrypetes) variolosa
(Variegated resin bee)
Heriades Species of the National Butterfly Center
Variegated resin bee
Heriades (Neotrypetes) variolosa
Size: 7 mm (female)
5 mm (male)
Associated plant at NBC:
This is a common species in
Cameron, Hidalgo & Starr Counties.
A female variegated resin bee (Heriades variolosa)
A female variegated resin bee
A dorsal view of the female bee: note the heavily-pitted head and thorax.
Scopal hairs of female bee
A male variegated resin bee: the curled-under abdomen is characteristic of male Heriades bees.
A male Heriades variolosa
Dorsal view of bee: note the coarse pitting on the bee's head and thorax, and the way each segment of the abdomen bells outward, a trait of all Heriades bees
Close-up of abdomen of male Heriades variolosa
CITE THIS PAGE: Sharp, Paula and Ross Eatman. "Heriades." Wild Bees of the National Butterfly Center of Mission, Texas. 15 Jan. 2019, http://www.wildbeestexas.com. Accessed [day/month/year guide accessed].