10
Bombus hortorum (Linnaeus)
This species has a relatively short season, and there are generally fewer workers to each nest
titan in the other common species. For these reasons it is somewhat less commonly observed, but
it may well be as common and widespread as the others. The queens emerge from hibernation in
late March, and workers are first observed about a month later. In general they resemble the
queens of Bombus lucorum, with yellow7 bands on the thorax and abdomen, and a white 'tail'.
However, there is a fringe of yellow hairs on the hind margin of the thorax (the 'scutellum') in
addition to the main one at the front. Also the head is long and narrow, compared with that of
lucorum, and the mouth-parts are long. The workers are similar in colouration, and very variable
in size. Fresh males and females emerge in late May and may be observed until the end of
August, or occasionally later. Males are similar in colouration to the females, and all are liable to
darkening of the yellow and white hairs.
As its name implies, it is a common visitor to gardens, but it occupies many other habitats where
conditions are appropriate for it. The females are adapted to nectaring from flowers with long
corolla tubes, and are particularly commonly seen at flowers of Honeysuckle, Comfrey and
Foxglove both in gardens and in woodland, river-banks and 'waste land'. Workers are typically
observed foraging from smaller Fabaceae such as clovers, vetches and trefoils, and Labiatae,
such as Deadnettles, Woundworts and Black Horehound.
Bombus pascuorum (Scopoli)
My earliest record for over-wintered queens of this species is in mid March, but they are
presumably on the wing earlier than this, as workers begin to appear at the end of March. Both
queens and workers are very variable in colouration. The ground colour is yellowish to ginger-
brown, mixed with variable amounts of black hair. The thorax is predominantly of the ground
colour, and has no distinct bands of yellow. This distinguishes it immediately from the other
common species. The abdomen is usually covered in yellow/ginger hair, with variable amounts
of black hairs. The latter are usually concentrated towards the front of the abdomen, and along
the sides. In particularly heavily marked examples, this gives the impression of a broad black
band on the abdomen. In other cases, the black hairs are few in number and examination with a
hand lens is sometimes needed to detect them. Fresh males and females begin to appear in early-
June in some years, but are often later. The males are similar in colouration to the females.
Colonies of this species persist into the Autumn with workers observed foraging well into
October. This is another very common and widespread species in Essex. Workers are able to
exploit a very wide variety of flowers, and are common in parks, gardens, hedgerows, roadside
verges and rough grassland throughout the county.
In addition to these six species of Bombus, a further five have been recorded in Essex since
1980. These are either very localised in rather specialised habitats, or are still widespread but
declining markedly.
Bombus ruderatus (Fabricius)
This species is very similar in appearance to Bombus hortorum. The queens are usually larger,
and the yellow a darker, more golden yellow. The band of yellow on the hind margin of the
thorax is wider in the middle than at the sides, and more-or-less equal in width to that at the
front of the thorax (the 'collar'). The yellow band on the abdomen is narrower than in hortorum,
and sometimes broken in the middle. Finally, the dorsal surface of the last segment is more
deeply 'sculptured' in ruderatus than in hortorum. According to the literature these features are
less clear in smaller workers, which may be impossible to determine. Males are also similar to
hortorum, but, again, the two bands on the thorax are of approximately equal width (hind one
Essex Naturalist (New Series) 16 (1999)