Bumblebees in Essex in 2001
Evidence now coming to light about B. muscorum as well as the other localised Essex species is
that they emerge from hibernation and establish their nests late in the season. It appears, therefore,
that nectar and pollen sources in late summer are crucial to the colonies reaching maturity and
producing fertile males and females. My immediate concern was that the early cut might have
eliminated the species along with flowering Vicia cracca, its main forage source at this site. However,
a visit on 20/08/01 revealed a small amount of V. cracca re-flowering, attended by very small
numbers of B. muscorum, both males and workers, one worker with full pollen loads.
Hopefully some discussion and monitoring of the management regime at this site might be possible.
It may be that an early cut of part of the grassland might prolong the flowering period of V. cracca
to the advantage of B. muscorum. On the other hand, virtual elimination of foraging sources in July
could be disastrous. It may be that the additional resources provided along the edge of the golf-
course, outside the Country Park, arc important (as suggested by the sightings on 20/07) when
these are scarce on the Country Park. However, since the 2001 season the path by the golf course,
and adjacent rough ground and ditches have been subjected to more intensive management, including
partial metalling of the path for cyclists. It remains to be seen how much more extensive this will
prove to be, and what effect it will have on the survival of B. muscorum.
B. humilis and B. sylvarum
I was able to make only one visit to the south Essex localities for these species in 2000. Accompanied
by Dr. B. Landells, the morning of 28/07/01 was spent at Wat Tyler Country Park, Pitsea. Most of
the commoner species were present in abundance, but despite intensive searches only two workers
of B. sylvarum were seen. B. humilis seemed to have fared a little better, and several workers and
males were observed. We then moved on to the Canvey Island stronghold of B. sylvarum, where, to
our dismay, the main area of Narrow-leaved Bird's-foot-trefoil Lotus glaber on which the species
had foraged in abundance the previous year was virtually bereft of flowering plants. No specimens
of B. sylvarum were seen. Several queens of B. humilis were observed foraging on flowering plants
of Bladder-senna Colutea arborescens, Red Clover Trifolium pratense and Broad-leaved
Everlasting-pea Lathyrus latifolius. However, these were very worn and clearly over-wintered
females which had still not established nests! A very few male B. humilis were also seen at the site,
indicating that at least one nest had reached maturity.
References
BENTON, T. (2000a) The Bumblebees of Essex. Lopinga, Saffron Walden, pp.87-8.
BENTON, T. (2000b) A Bumblebee new to Essex. Essex Field Club Newsletter, 33: 18.
Essex Naturalist (New Series) 19 (2002)
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