THE 1999 AGM ADDRESS
Bumblebees in Essex
PROFESSOR E. BENTON
13 Priory Street, Colchester COl 2PY
The Bumblebees are a group of social insects which arc well-known to, and often highly valued
by the general public. Their role in pollination of agricultural and horticultural crops is widely
recognised, and concern about the decline of many British species has gained considerable
media coverage. The 'varroa' mite epidemic affecting honey bees has thrown attention on
Bumblebees as a possible alternative pollinator for some crops: the Daily Telegraph, for
example, ran a story in 1992 under the heading 'Bumble bee flies to rescue of farmers'.
Unfortunately, as the article pointed out, the farmers had not been particularly kind to the
Bumblebees, and salvation would require urgent action to restore destroyed Bumblebee habitats.
Introduction
Bumblebees belong to the insect Order
Hymenoptera, which also includes so-called
'solitary' bees and wasps, ants, saw-flies and
the parasitic ichneumon 'wasps'. The family
to which they belong (Apidae) is shared with
the familiar honey bee (Apis mellifera). Like
other Hymenopterons, Bumblebees have two
pairs of wings, and six fully developed legs.
They arc best known for their 'furry'
appearance, and they also have a distinctive
flattening of the tibia section of the hind legs.
This has a fringe of long, curved hairs which,
in queens and workers forms a 'corbiculum',
or pollen basket used for collecting and
transporting pollen. The characteristic
alternating pattern of white, yellow and black
which is shared by several species functions as
a 'warning' sign for potential predators. This
has made possible the evolution of mimics of
Bumblebees in other insect Orders, and this
can cause confusion for the beginner. Several
species of Hoverflies (Syrphidae) are
astonishingly accurate mimics, three of them
(Eristalis intricarius, Merodon equestris and
Volucella bombylans) being common in
Essex. Another very familiar fly of early
spring, Bombylius major, closely resembles a
small worker of Bombus pascuorum.
The mouthparts of Bumblebees are adapted
for sucking up nectar, and in some species
they are particularly elongated, enabling the
bees to access flowers with long corolla-tubes.
In the process they brush pollen onto their
bodies, and periodically stop to scrape the
grains into the pollen basket with the aid of
their fore-legs. An incidental consequence, so
far as the bees are concerned, is that they
transfer pollen from plant to plant as they
forage. Some species, however, have the
ability to bite holes in the base of the corolla
tubes, and so access the nectar without
brushing against the the anthers. Although
quite a lot of research has been devoted to
associating tonguc-lcngth in Bumblebees with
preferences for particular types of flowers, this
is inconclusive. Some species show definite
preferences. Bombus hortorum is most
frequently seen foraging from such flowers as
Honeysuckle and various 'deadnetlles', whilst
Bombus lapidarius workers are most
commonly to be seen on the flowers of smaller
species of Fabaceae (clovers, trefoils and
others), but most are 'generalists'. The crucial
habitat-requirements for most species - apart
from suitable nesting and hibernation sites -
are abundant nectar and pollen sources for the
whole foraging-season. Particularly important
are early-flowering plants to provide food for
females as they emerge from hibernation and
establish their nests.
Essex Naturalist (New Series) 16 (1999)