Bees, butterflys, lacewings and more! Here are details of the insects to consider when building bug hotels.
In Britain we have around 270 species of bee, just under 250 of which are solitary bees. These bees can be amazingly effective pollinators and as the name suggests tend not to live in colonies like bumblebees and honey bees.
Only the female Solitary bee has a sting which is very feeble compared to other bees and will only ever sting you if you handle them roughly or pose a threat to them. Being loners, Solitary bees fly around by themselves and do not attack in swarms or groups like some other types of bees.
Generally, they are absolutely harmless. Solitary bees do not even bother to protect their own nests. Solitary bees create nests in hollow reeds or twigs, holes in wood, or, most commonly, in tunnels in the ground.
Solitary bees in Britain are highly diverse, therefore so are their nesting habits. The majority of British species nest in the ground, excavating their own nest.
A number of species also nest aerially, usually in old beetle holes often sealing the nests with a saliva like substance, mud, chewed leaves, resin or sections of leaves which they cut with their jaws. These species are the ones most likely to take to artificial nests in gardens. There is also one species of solitary bee in Britain, Ceratina cyanea, that excavates its own aerial nest, usually in bramble stems. This small metallic blue bee excavates out the pith of the bramble stem and nests in there. Unusually both the males and females also overwinter, hibernating in the stems.
Finally there are the snail shell nesting bees, of which we have three species in Britain. They use chewed up leaves to seal off the each section in the empty nest shells and often camouflage the shell in some way.
There is only one species of honey bee in the UK. It is the honey bee that is the bee that stings. It lives in cavities about 40 litres in volume, which is enough space for 10,000 to 50,000 bees. Honey bees will not go anywhere near a bee hotel.
These bees collect sections of leaves in which they build their aerial nests in old beetle holes. There are 7 species in Britain, all of which look rather robust and have large jaws. Pollen is collected by females on the scopal hairs on the underside of the abdomen. Remarkably up to 40 pieces of leaf are needed just to build one nesting cell for one offspring. Leafcutter bees are parasitised by bees in the genus Coelioxys. This is a group of species that you can attract to your garden by providing a bee hotel.
There are 11 species in this group found in the British Isles, all of which are aerial nesters in holes in wood and are rather small, averaging 6-7mm long. These bees are often called yellow-faced bees as they usually are black with patches of yellow on their faces. This group doesn’t have any pollen collecting apparatus so collect pollen and nectar in their crops before regurgitating it back at the nest.
There are 11 species in this genus, all of which collect pollen on the underside of their abdomens. Their life histories are all very interesting and vary dramatically though with some species nesting in snail shells and others nesting aerially in stems. Some of these species are generalists, collecting pollen from a variety of plant species, while others are very specific.
This is probably the most familiar solitary bee to many people. This species flies in a single brood from March to July and abundant in lowland England and Wales. It is however uncommon in Scotland and Ireland (where it has recently been introduced). The females of this species are quite large (9-14mm long) and use mud to build their nests in a range of natural cavities. This mud is carried beneath the head and seals off the individual sections of the nest. This species takes rapidly to artificial bee hotels and due to its efficiency at pollinating fruit trees, is sometimes introduced to orchards.
Most commonly nests in dense aggregations in sunlit, vertical surfaces such as coastal sandstone cliffs, sand pits, roadside cuttings, cob walls and in soft mortar joints of brickwork. The bee has gained some notoriety in undermining mortar joints, in extreme examples leading to serious weakening of masonry, with piles of excavated sand collecting at the bases of affected walls. Individual nest burrows generally terminate either in a single cell or in a series of 4-10 consecutive cells, the convex base of each fitting into the concave lid of the previous cell.
This small slender black bee is closely associated with Bellflowers (Campanula species) and is a frequent, though overlooked, visitor to gardens and parks. Both sexes are a similar size (6-7mm).
Small beetle holes in dead trees or woodworm holes in old sheds and fences are used for nesting.
Planting various Bellflowers and providing nesting sites (in the form of dry reed stems) can encourage the species into gardens.
A large, bumblebee sized species, that often nests in the soft mortar and exposed cob of old walls. Occasionally it will nest in the ground, preferring bare compacted clay soils. Flies from late February to mid-June, and is extremely fond of visiting Lungwort (Pulmonaria) flowers. Look for the swift-darting flight. Often approaches the flower with the long tongue extended
Females select existing cavities as nest sites, examples including insect exit burrows in dead wood, hollow stems, crevices in the mortar joints of masonry, burrows in the soil, and various man-made objects. The cell walls and closing plug of the nest are fashioned from compacted layers of long, silky hairs which are shaved off leaves by the female’s multi-dentate mandibles. Hairs are brought to the nest site in a ball and applied to the inner surface of the cavity by teasing them out with the mandibles; the gaster is then used to tamp down the hairs. The species has earned the colloquial name ‘wool-carder bee’ from this habit.