Yellow Cuckoo Bumble Bee, Bombus citrinus

Excerpted from Bumble Bees of Wisconsin

Yellow Cuckoo Bumble Bee, Bombus citrinus The lemon cuckoo is a nest parasite of the common Eastern Bumble Bee, the Two-spotted Bumble Bee and the Half-black Bumble Bee. The cuckoo bee locates a host nest by trailing chemical signatures left by host workers. After locating a host nest the cuckoo will revisit to further observe the nest and will proceed to infiltrate if she determines the nest to be suitable for a successful usurping.

  Physical Description

Like all cuckoo bumble bees, the outer tibial surface of the hind leg is convex and densely hairy, rather than adapted for pollen transport. Their heads are more tear-drop shaped and the thorax is predominantly yellow including the lower sides. Hair on the face is usually black with some yellow hairs, there are usually no black hairs on the thorax and would not form a band between the wing bases. The wings are slightly opaque ranging from a reddish brown to brownish black and yellowish during pubescence. They are sometimes interspersed with black hairs.

  • Queen length: 21-23 mm
  • Female Worker length: 9-14 mm
  • Drone length: 12-14 mm


Only new, mated queens overwinter, emerging from diapause (a form of hibernation) in the spring. New queens kill or subdue the queen of a host colony and lay eggs, which the host colony raises. The resulting cuckoo bee offspring are all queens or males. New queens mate and enter diapause.

  Activity Period

Yellow Cuckoo Bumble Bee, Bombus citrinus activity period The majority of observation records in Wisconsin took place June to September.


Yellow Cuckoo Bumble Bee, Bombus citrinus graphic The lemon cuckoo bumble bee is known from eastern U.S. and Canada. Studies have shown declines in Canada, but not in Illinois and eastern U.S. Wisconsin's historic records show it found statewide but most widespread in the southern part of the state.

  Feeding Habits

Cuckoo bumble bees do not have the ability to collect pollen and thus lay their eggs in the colonies of other species to raise their young (Hatfield et al. 2014).

  Bumble Bee Videos

 Buzz Pollination
 Slo-Mo Footage of a Bumble Bee Dislodging Pollen
 Look Inside a Bumblebee Nest
 How to Build a Bumble Bee House
 Development of Colony and Nest in the Bumblebee

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