Bumblebees

All the bumblebees shown below are often seen
in gardens during spring and summer . . . . . .

Bumblebees and honeybees are grouped together by entomologists into the family Apidae or social bees, and form part of the insect order Hymenoptera, which also includes solitary bees, wasps, ants, sawflies and ichneumon flies. Honeybee colonies are perennial, but bumblebee colonies are annual affairs which die-out each autumn, leaving only young mated queens to survive winter and start new colonies again each spring (rather like the social wasps). All the fairly large bumblebees seen flying in early spring, are overwintered queens busy feeding and searching for nesting sites after their long hibernation. Some bumblebees nest in cavities underground, often taking over old mouse holes (1, 2 and 3 above), whilst others nest on the ground surface in rough grass or moss (4 above). The nest comb and brood-cells are made from a waxy material produced by the bees from special wax-glands on their bodies, and the whole nest is usually covered and protected inside a ball of dead, finely shredded grass, moss, animal fur or similar material.

Bumblebee Nest
(exposed to show brood cells)

The smaller bumblebees seen foraging on flowers through most of the summer are workers. The queen rears the first brood of workers herself, but then the worker bees take over the duties of collecting food, rearing the young and building and maintaining the nest, whilst the queen devotes herself to egg-laying.

Bumblebees feed on pollen and nectar, and rear their grubs on the same diet. In this respect they differ from wasps, whose young are fed on a meat diet of caterpillars and other insects. Towards the end of summer bumblebee colonies produce males and new queens. The males (or drones) do no work in the colony and quickly leave the nest to search for, and mate with, the new young queens from other colonies. Once fertilised, the young queens also abandon the nest to start their winter hibernation - usually in small underground chambers in well drained soil, often under stones, logs or in grassy banks. Male bees die after mating, and when the young queens have departed, the rest of the colony soon perishes and dies.

Bumblebee queens and workers can sting, but rarely do so except in their own defence and, usually, only if actually handled - SO AVOID PICKING THEM UP! Unlike wasps, bumblebees are generally quite docile and non-aggressive, and go about their business with little attention to human activity, even when this is close to the nesting site. If a colony is unearthed or disturbed, for example when gardening, it should be left alone and simply covered over again. The bees will quickly repair any damage and carry on as before. There is no real justification for destroying bumblebee colonies. Mostly they go unnoticed, but a small inconvenience due to the position of a nest is more than repaid by the immense value of these insects as pollinators of many wild and cultivated plants. Pollination in some crops, like runner beans and field beans, depends almost entirely on the foraging activity of bumblebees or honeybees. Few, if any, bean flowers will set pods unless visited by these insects. Likewise, many varieties of apples, pears and plums produce more fruit when bees are plentiful on the blossom. If you are a keen gardener with an interest in conservation, then why not try some simply measures to encourage bumblebees and reap the pleasure and benefit of their industrious activity.

Measures to encourage bumblebees:

• Planting Sallow or Pussy-Willow (Salix caprea), Winter Heather (Erica carnea), Mountain Windflower (Anemone blanda), Crocus and other spring bulbs, will attract and provide food for young nesting queens.

• A sequence of summer flowering annuals and perennials, together with flowering shrubs like Crab Apple (Malus), Cotoneaster, Buddleia, Honeysuckle (Lonicera) and Summer Heathers (Calluna vulgaris and Erica cinerea), will help provide a continuous supply of pollen and nectar for developing colonies.

• A pile of grass cuttings and moss raked from the lawn and left in a sunny, secluded corner of the garden, can provide a good nesting site for carder bees.

• Some bumblebees can be enticed to nest in small domiciles or nest-boxes placed on the ground, in a hedge bottom or other sheltered place.