Extracted from 2017 Bees of Maryland: A Field Guide http://bio2.elmira.edu/fieldbio/beesofmarylandbookversion1.pdf
Common and, at times, dominant bees, that occur in all habitats, but reach their peak
abundance in the spring with a few species emerging in the fall and a very few species
out in mid-summer.
Field Marks: ♀♂Thorax and abdomen integument entirely black, with
varying degrees of white to ochre hair (usually dense and long on thorax). ♀Face,
shallow depression (fovea) lined with minute hairs that reflect a white color (rarely
chocolate brown) making the fovea relatively visible in the field; fovea roughly
oval, though shapes vary, and runs from the top of the head between the ocelli and
the eye down and usually narrows beyond the gap between the antennal socket and
eye. Note that the foveae are usually surrounded by longer hairs. Note: 2 very rare
summer/fall females have yellow patches on their lower faces all other species have
black. ♂Face, with long pale hairs; hair usually particularly dense below antennae
and overhanging, beard-like, the clypeus rim. Face, clypeus (and at times to the
sides of clypeus) in with bright yellow marks in some species. Body and head
relatively wide compared to similar genera. A few species with reddish/orangish
lower legs.
Flight Season: Abundant in the spring, nearly absent in summer, regular in the fall
Size Relative to Honey Bee: 0.5 - 1.5X
Position of Wings Feeding on Flowers: Held slightly to sides or completely
overlapping on back though the less common fall species regularly hold their wings
out to the side.
Location of Pollen Carrying Hairs: Hind femur, trochanter, tibia, back sides
of thorax (propodeal corbicula), the joint between legs and thorax, in particular.
Similar Genera: Large hair-filled foveae are unique to Andrena. Halictus -
Abdomen, segments, rim with crisp, thin, narrow bands of small, prone, white, hairs
along the rim of the abdominal segments; Andrena species can also have hair bands,
but they are usually fluffier, often missing in the middle of the segment, and not on
every segment. ♂Head longer than wide, yellow in patches on legs. Melitta - (very
rare group) ♀Face, without foveae. Legs, carries pollen on tibia and basitarsus only,
does NOT carry pollen on side of thorax or on femur. ♂Approximately Honey Beesized
and may not be separable from Andrena in the field. Colletes - Face, distance
between inner edges of eyes strongly decreases from top of head to mandible.
Nest: Ground, often in open bare soil, but can be underneath leaves/leaf litter.
Flowers: Almost any flower. Many species are specialists on individual plant genera.
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