A common sight in some gardens and allotments, a few parks and woods, and very few fields is that of a large bumblebee flying low to the ground looking as if she has lost something. She is looking for a suitable underground nest site, ideally an old mouse burrow. Bumblebees have been evolving for more than 100 million years and we must assume that much of their behaviour is programmed and performed without the need for thinking. Oh yes, they must be able to think because they can learn to make choices about which flowers to visit, how to organise their foraging trips efficiently, how to control the temperature of the nest, etc and all of this relies on a healthy immune system.
Nest sites are also spotted by using sight and scent. The bumblebee eye can detect ultra-violet light and can thus see components of mouse urine on the runways. The selection of flowers also uses this UV sensitivity.
The life and co-ordination of activities within the colony, depend very heavily on chemical molecules produced by individual bees, and the antennae on the head have receptors that are incredibly sensitive. Even we can smell mouse urine, but bees are real experts and use this ability.
The Buff-tailed bumblebee (B. terrestris) is the species that you are most likely to see locally. Some of the queens that have been visible over the last few months have been huge, and a tribute to gardeners who provided good supplies of food during last summer and autumn while these queens were only grubs being fed in the nest. They have a yellow-brown band on their thorax, another on their abdomen, and a white tail. The tail often looks off-white and may have a visible brown band next to the black fur.
Because they have short tongues, Buff-tails choose open, shallower flowers like Poppy, Cotoneaster, Gorse, Crocus, and a wide variety of other species throughout the year. Their families are large with up to 500 workers in a brood and often more than one colony in a year.
Consider filling your gardens with flowers of known benefit to pollinators, like Wallflower, Snapdragon, Scabious, Anemone, Cornflower, Poppy and Cosmos to give yourself visual pleasure and the deafening approval of local bumblebees. Recoil from the thought of using insecticides! Get rid of your strimmer so that small insects can live at the base of hedges. Reduce the area of grass that you mow and allow the daisies to flourish. You could let your creative side show by creating interesting paths through the sward! Then just sit back and listen to the hum…
Adrian Doble (Bumblebee Conservation Trust) April 2021