Mining Bees (Andrenidae)
The islands and peninsulas that formed above the Weald Moors at the end of the last Ice Age have long been a refuge from the watery peatlands around them. Drier and more free draining in nature, the lighter soils of these traditional crop-growing areas also attract a range of wildlife, too, including a group of insects that would otherwise be ill suited to moorland life…
ID: Andrenidae are wild bees that excavate nests in the ground, a trait that has collectively endowed them with the more familiar title of ‘mining’ bees. There are round 60-80 Andrena species in the UK, with considerable variations in size between each. While they can be difficult to identify, the larger of them are similar in size to bumblebees, but are generally a little slimmer in appearance and less hirsute. For the especially eagle-eyed, there is also a sub group of ‘midget mining bees’ (Micrandrena), the identification of which is really the preserve of experts.
In the Field: when it comes to nesting, Mining bees have a strong preference for firm, sandy soils that are generally free from undergrowth. Garden lawns, field paths and roadsides are all typical locations where their excavated mounds of earth (similar in appearance to wormcasts) might be found, although grassland is also utilised by some species. The nests themselves consist of a single tunnel (generally around 20-40 centimetres in depth) with an entrance that is roughly equivalent in size to a ten pence piece. Mining bees are solitary in nature and do not form colonies, although they often nest in close proximity to each other.
Nomadic Cuckoos: if you come across some suitable mining bee habitat in on your moorland travels, remember to look out for Cuckoos in your midst. Not, in this instance, the avian variety but, rather, the Hymenopteran equivalent. Nomad bees, which really look more like small wasps, acquire their name from the habit of flying low over the ground in questing fashion. The purpose of their wandering is to locate the whereabouts of mining bee nests, especially Andrena species. Nomads, you see, are ‘cleptoparasites’, which essentially means their larvae obtain nourishment from a host’s eggs. So, while a mining bee is out and about busily collecting nectar and honey for its brood (which usually number no more than half a dozen) the nomad sneaks in unattended and lays its own egg in the nest. The reason this invasive activity proves so disastrous for the mining bee’s offspring is because in its first stage of development (known as an ‘instar’) the nomad’s larvae is equipped with large mandibles, which are used to gobble up everything else in the nest! As they rely on Mining bees to provide parental care for their offspring, Nomad bees are not adapted to collect pollen and nectar. However, they do visit flowers and Hogweed, Germander Speedwell and Dandelion are common species upon which you may find them feeding.
On the Weald Moors: when it comes to finding Mining and Nomad bees on the Weald Moors, the island farmstead of the Buttery is a location with a strong track record of hosting them. The open, bare trackside ditch banks leading from the farm down to the reservoirs on Kynnersley Drive are often alive with groundnesting bees in spring and early summer. Among the most common is the Early Mining Bee (Andrena haemorrhoa), which, as its name implies, is on the wing from around March. It has a black abdomen bookended by a foxy brown thorax and tip. The Grey-patched Mining Bee (Andrena nitida) is another large species that also has foxy brown hair on the thorax but whose black abdomen is more polished in appearance. It is right on the edge of its northern range in Shropshire, and is on the wing from April to June. Andrena minutula, which measures just five to seven millimetres in length, is the commonest of our Mini-mining bees. Males and females of this species both have a black thorax, which is shiny in the former and dull in the latter. On the wing from March to September, they forage on a wide variety of flowers and blossoms.
Such is the way of things that each species of Mining bee is often targeted by its own particular Nomad. Where you find Andrena minutula, for instance, Nomada flavoguttata often follows, and so it is at the Buttery, where this distinctive species (which has a black and red banded abdomen, with small yellow spots on the side) is a known parasite! Similarly, the distribution of Early Mining Bees in our countryside is almost mirrored by the Common Bee Wasp (Nomada ruficornis), with which it also shares comparable flight times. Much like a wasp, it has a black and yellow banded abdomen that is also covered by notable red blotches. Gooden’s Nomad Bee (Nomada goodeniana) is another black and yellow banded species found at the Buttery. While it is known to target several Andrena species there is evidence to suggest it has an association with the Grey-patched Mining Bee. If you’re able to gain a close look, watch out for its distinctive orangey-red legs and antennae, and an unbroken second yellow band on the abdomen that marks it out from other Nomada species.