There are around 276 species of bee in the UK, many of which are common and widespread. Most British bees are solitary, the female stocking the nest with supplies of nectar and pollen for the larvae by herself (though some species may nest communally and may even have the same entrance for different cells). A small numbers of British bees are social, with a queen producing eggs which are raised by female workers. These are the familiar Bumble-bees and also the Honey Bee. Some species can be both; the common ‘sweat bee’ Halictus rubicundus (below) for instance is solitary in northern Scotland, but social in southern England.
The remainder of British bees are nest-parasites of one form or another. Parasites of solitary bees come in various shapes and sizes and use a variety of methods to ‘steal the stash’ as it were. Some, such as the Nomad Bees (Nomada spp.) sneak into a developing nest while the female host is not looking and lay their eggs. Other such as the Blood Bees (Sphecodes spp.) may open up a closed cell and lay their egg, while Large Sharp-tailed Bee (Coelioxys conoidea, below) females use their blade-like ovipositor to cut into the nest of Leaf-cutter bees. In all these cases, either the adult nest parasite, or usually the larva, destroy the host egg or larva and then consume the food stores laid in by the host.
Image: Peter Stoppard
The nest parasites of bumble bees are called Cuckoo Bees and do things slightly differently. The adult female sneaks into the nest of the host species and kills or usurps the queen. She then lays here own eggs in the nest which are raised by the workers of the old queen. Cuckoo bees are closely related to bumblebees and look very similar, though they tend to have darker wings and sparser hairs (as well as thicker cuticle as a defence against stings from defending workers). Red-tailed Cuckoo Bee (Bombus rupestris, below) is a nest parasite of the familiar Red-tailed Bumblebee, Bombus lapidarius).
Bees collect pollen to stock their nests, initially collecting it on their hairy bodies before brushing it in to specialised areas generally on their legs of abdomen (some species even carry it in their crop). Bumble-bees for instance have specialised areas on their hind legs known as ‘pollen baskets’ while species such as the Patchwork Leaf-cutter Bee (Megachile centuncularis) and Red Mason Bee (Osmia bicornis, below) have similar areas under their abdomen. As they often transport pollen between different plants of the same species they are very important pollinators for a range of plants. Around 80% of wildflowers are pollinated by bees as well as about a third of the food we eat including vegetable such as broccoli, asparagus and cucumber and fruits such as apricots, apples and tomatoes.
Females of all British species have a sting for defence (an evolved ovipositor) though few are able to pierce human skin. As a consequence many have warning colouration, with often striking combinations of red, white, yellow and black (think of the familiar bumblebees). In some cases, groups of these species evolve to look more like each other as time goes by (again, some bumblebees are a good example), eventually forming what is known as a ‘mimicry ring’. Mimicry where several poisonous or venomous species evolve to look like each other is known as Müllerian mimicry. Many non-harmful species also mimic bees (known as Batesian mimicry) to protect themselves from predators. For instance, the Bear Hoverfly (Criorhina berberina, below) is a mimic of the Tree Bumblebee (Bombus hypnorum, bottom).