Bombus citrinus

Lemon Cuckoo Bumblebee
Bombus citrinus

Lemon Cuckoo Bumblebee Bombus citrinus male
Lemon Cuckoo Bumblebee Bombus citrinus male on Blazingstar Jul 17, 2008 Wheatley, Ontario.
Lemon Cuckoo Bumblebee Bombus citrinus male
Lemon Cuckoo Bumblebee Bombus citrinus male on Cup Plant Aug 12, 2007 Wheatley, Ontario.
Lemon Cuckoo Bumblebee Bombus citrinus female
Lemon Cuckoo Bumblebee Bombus citrinus female on Blanketflowers Jun 23, 2007 Wheatley, Ontario.
Lemon Cuckoo Bumblebee Bombus citrinus female
Lemon Cuckoo Bumblebee Bombus citrinus female on Sumac flowers Jun 29, 2008 Wheatley, Ontario.
Lemon Cuckoo Bumblebee Bombus citrinus male
Lemon Cuckoo Bumblebee Bombus citrinus male Aug 12, 2009 Wheatley, Ontario.
Lemon Cuckoo Bumblebee Bombus citrinus female
Lemon Cuckoo Bumblebee Bombus citrinus female on Sumac flowers Jun 21, 2009 Wheatley, Ontario.

Identification:
Female:
Head: Top of head has yellow hairs with a few black intermixed. Hairs are usually all black near antennae. No black bar on thorax.
Thorax: Narrow centre spot bare, shiny; surrounded by dense, but short yellow hairs. Thorax sides yellow.
Wings: Lightly tinted, veins brown to blackish.
Legs: Brown with black hairs. Feet (tarsi) brownish with yellowish hairs.
Abdomen: Black dense short hair. Segment 3 and/or 4 may be yellow or with thin yellow stripes. Abdomen tip shiny bare, protruding yellowish to reddish.

Male:
Head: Black, hairy with very few yellow hairs mixed in with the black on a line at the back of head.
Thorax: Centre spot large, usually rounded and entirely black between wing knobs – sometimes appearing as a wide stripe, especially when viewed from the side. Surrounded by very long, dense yellow hairs. Sides with long yellow hairs.
Wings: Lightly tinted, veins brownish-yellow to dark.
Legs: Black hairs; some obscure pale fringe on front of brownish feet (tarsi). Underside of shins (tibiae) reddish pile.
Abdomen: Segments 1 and 2 have very long yellow hairs; sometimes 2 has black at the segment base and on sides. Segment 3 can be black or yellow, but usually has some black at centre. Segments 4 to 6 black. Tip shiny, protruding.

Similar Species: Bombus insularis is in Kent County, the female has an obvious black band on thorax between wing knobs, and the male has a mostly yellow abdomen. The Confusing Bumblebee Bombus perplexus males have thorax entirely yellow, except for a tiny mid black spot.

Size: Female 17 to 21 mm long. Male 13 to 15 mm long.

Flight Time: Late May to early October.

Habitat: Forest edges and meadows where the Common Easter B. impatiens and the Half Black B. vagans are present.

Food: Nectar from flowers, but does not collect pollen for offspring.

Life Cycle: Females lay eggs in the nests of Bombus impatiens and B. vagans, making these unrelated workers feed and care for the new B. citrinus queen and her larvae. The queen Lemon Cuckoo flies later in the year than other bumble bees in her search for a nest that has enough workers to tend her young but not enough to successfully repulse her attack on the colony. The females can displace or kill the host queen and seem more able to suppress worker ovarian development.

Comments: Essex County – Point Pelee National Park, Ojibway Prairies; Colchester and Pelee Island. Kent County – Rondeau Provincial Park.

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