Ashton Cuckoo Bumble Bee, Bombus Ashtoni
Excerpted from Bumble Bees of Wisconsin
The Ashton Cuckoo Bumble Bee is very rare and is declining rapidly. Historically it is known from the eastern and
midwestern U.S. As of 2015, it is only known from seven sites in North America. Wisconsin has a handful of
historic observation records from northern and northeastern counties. The species was last reported in
Wisconsin in 1979.
The Ashton Cuckoo Bumble Bee is a nest parasite of the Rusty Patched Bumble Bee and the Yellow Banded
Hair medium and even. Thorax yellow, with a straight or “T” shaped band of black hair between the
wings. First abdominal segment fully yellow, with the second segment yellow and usually containing a
patch of orange or rusty-brown hair. Unlike B. griseocollis, this patch is entirely surrounded by yellow
hairs. Queens often without the rusty-patch, making the second abdominal segment entirely yellow.
Males have similar color patterns to workers, but occasionally with more brown hair on the second
abdominal segment. Males also lack corbiculae, or the flattened midleg of the hind leg used for
Ashton Cuckoo Bumble Bees lay their eggs in the colonies of other species to raise their young.
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.
Historically, the majority of observation records in Wisconsin took place in August. Earliest records
were in April and latest in October.
Habitat types are variable, and likely depend on host species. Overwintering sites are unknown.
Ashton Cuckoo Bumble Bees do not have the ability to collect pollen.
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