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Triepeolus / cuckoo Bee

Family: Apidae

Genus: Triepeolus

Common Name: Cuckoo Bee


Physical Appearance

Triepeolus species have a thick cuticle to withstand attack from their hosts; they typically have wasp-like features and coloring. They typically have a dark integument with wide, somewhat irregular looking pale yellow banding on the thorax and abdomen.

Since the female does not forage or provision nests for her offspring, she lacks the specialized hairs on either her hind legs or abdomen to carry pollen.


Cuckoo bees detect the nests of their host bees by their particular scent. Once the host nest is detected, the female cuckoo bee will loiter near the nest entrance, waiting for the host female to leave on a foraging trip – when the host female has vacated the nest, the female cuckoo bee slips into the nest and lays her own eggs.

The developing larvae of cuckoo bees have large, sickle-shaped jaws which are used to destroy the host egg or larvae, thus commandeering all the food provisions for their own nourishment.

Approximately 20 percent of North American native bee species are cuckoo bees.

Size: Small to medium size bees, 1/2 to 3/4 inch.



Triepeolus are most prevalent in North America, and are found across the United States and Southern Canada. The greatest diversity of species occurs in the West and Southwest United States.

Number of species in North America

Approximately 100


Emergence Time
Spring to summer, depending on species


Nesting Habit
Triepeolus species are kleptoparasites - that is they lay their eggs in the nests of other bees that that have already been provisioned with food stores by the host. While bees in the genus Melissodes and Svastra serve as the primary hosts for many Triepeolus species, the females belonging to this kleptoparasite group are known to lay their eggs in the ground nests of a considerable range of host bee genera.

Visited Plants

Bidens / Beggarticks

Chrysothamnus / Rabbitbrush

Coreopsis / Tickseed

Cucurbita / Gourd

Gaillardia / Blanketflower

Grindelia / Gumweed

Helenium / Sneezeweed

Helianthus / Sunflower

Ratibida / Prairie Coneflower

Rudbeckia / Coneflower

Solidago / Goldenrod

Verbesina / Wingstem

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