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Bombus
pascuorum has a medium length tongue and can often be found foraging on
clovers, vetches, blackberries, and later in the year on thyme sage and
lavender. It often nests at the base of a tussock of grass, and some say it can
be aggressive when disturbed, even chasing after people. However when observed
during foraging it is no more aggressive than any of the other species. The
workers and males look similar to the queen, but are a little smaller. The
photgraph on the left was sent in to me by a visitor to the site, and shows
typical behaviour of scrabbling around in grass, and pulling bits into their
nests.
This queen above left has her tongue sheath extended, her tongue is
inside and is longer than the sheath. Although there are a few species of
ginger coloured bumblebees in the
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UK this is by far the most common in nearly
all areas. The hairs of the abdomen are lighter in colour to those of the
thorax, and have a few black hairs. In a very sunny summer such as 1995 the
hairs of older bees can become faded and appear beige in colour. The thorax is
always covered in hairs, with other bumblebees there is sometimes a bald patch
in the centre of the thorax. This can be caused by wear as the bees rub against
the side and roof of the nest, but this is hardly ever seen in Bombus
pascuorum. If there is a complete absence of black hairs on the abdomen,
then the bumblebee is probably not B. pascuorum, but either B. humilis or B. muscorum.
Lengths, queen 16-18,
workers 10-15, male 13-14.
On the left is a worker (female), and you can clearly see the 3 ocelli (simple eyes), as well as the compound eyes. |
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When I was
marking bees in order to follow them and record their
foraging behaviour I found that B. pascuorum was the most difficult to
mark as its thorax was so hairy. Early in the
summer, before it has been bleached by the sun the hairs are a beautiful, rich
ginger colour as you can see in the photographs above.
B. pasucorum nests just below ground in old mammal burrows, or on the surface in gass tussocks. Successful nests can have as many as 150 workers. After founding the average nest lasts for about 25 weeks.
The cuckoo species is B. campestris.
I believe that this bee is
suffering from the recent habit of farmers cutting their grass for silage in
June/July instead of for hay in August. In Scotland the queens have just
established their nests but have few workers when the nests are destroyed by
the tractor. Some queens will be killed sitting on eggs, others will have the
onerous task of establishing a nest again. Fortunately it is still a fairly
common bee, and is very valuable for pollinating the more "difficult" flowers such as antirrhinum, left, where an inexperienced forager hesitates before plunging into the gullet of the flower allowing the top peral to fully enclose her. Only a heavy and strong insect such as a bumblebee can get into such flowers. |
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