Bumblebees

Flowers carry a small negative charge; a bee in flight carries a small positive one. That difference creates a weak electric field around a bloom, and it changes measurably after a bee has landed on it — which could tell the next visitor the nectar has already gone.

A bumblebee colony is annual. A mated queen spends the winter alone underground, emerges in spring, and searches at low level for a nest site — usually an abandoned rodent burrow, a tussock or a cavity. She builds a small wax pot, provisions it, and raises the first brood herself. Those daughters become workers, and from then on she does nothing but lay.

The colony grows through summer to somewhere between fifty and four hundred workers, depending on species, then switches to producing males and new queens. Once those have flown and mated, the founding queen, the workers and the males all die. Only the new mated queens survive the winter, and each of them starts again alone.

This is why a large bumblebee seen in early spring is almost always a queen, why nests appear and vanish within a season, and why a nest found in August is close to finishing on its own. It also explains the vulnerability: the whole next generation of a colony passes through a bottleneck of one animal.

Adults live on nectar; the pollen goes to the larvae, packed into the corbicula — the smooth, fringed hollow on the hind leg that gives a laden bumblebee its lumpy yellow trousers. Bumblebees store only a few days of food in small wax pots, which is why cold wet weather at the wrong moment can starve a colony that looked healthy.

Some flowers hold their pollen inside tubular anthers that open only through a small pore, and will not release it to a visitor that simply walks about. A bumblebee grips the anther, disconnects its wings from the flight muscles and vibrates them, shaking the pollen out. Tomatoes, aubergines, blueberries and cranberries are all pollinated this way. Honey bees do not do it, which is the practical reason commercial bumblebee colonies are put into tomato glasshouses.

Yes, and unlike a honey bee worker a bumblebee survives it: the sting is smooth rather than barbed, so it can be used more than once. In practice they very rarely do. A foraging bumblebee has no colony to defend where it is standing, and the usual defensive display near a nest is to raise a middle leg or roll onto its back with the sting presented, rather than to fly at anyone.

Males cannot sting at all — a sting is a modified ovipositor, so no male bee or wasp of any species has one. The large bumblebees patrolling a hedge in late summer are often males, and cannot do anything to anybody.

Bumblebees are round, densely furred and banded, and carry pollen openly on the hind legs. The animals most often mistaken for them separate on covering and shape more reliably than on colour.

Beyond that, identifying a bumblebee to species from a photograph is genuinely difficult and often not possible — tail colour, band pattern and hair length vary within a species and overlap between them, and several common species have colour forms that look like each other. NatureHQ does not attempt species identification, and treats anything that claims to do it from a single photograph with caution.

Wild bees fared worse than managed honey bees in the largest field test to date. They are also far less monitored, which means the decline of the species that do most wild pollination is the part we know least about.

It is worth separating two questions that are usually merged. "Are bees dying?" is normally asked about honey bees, which are livestock and whose managed colony numbers have risen globally over recent decades. The species genuinely in trouble are wild — bumblebees among them — and their decline is driven mainly by habitat and forage loss, with pesticides as a well-evidenced additional pressure rather than the whole story.