South Staffordshire, including the Black Country, is famous for its coal and limestone, but insect miners have been at work here far longer than human ones. Mining bees in particular remind us of their presence throughout the spring months. They are responsible for those little volcano-like mounds of soil which suddenly appear in our gardens and greenspaces at this time of the year. They are especially noticeable on sandy paths and close-mown grass.
The bees are cousins to bumble and honey bees, but are all solitary, in that they do not live together and tend a hive, although several females will excavate clusters of mines in suitable places. They make burrows up to 60cm. deep in which they lay eggs and provision them with nectar and pollen. There can be up to five mini-mines branching off the main one. Sometimes two or three females will use the same entrance hole before making their own branch mines once underground.
There are scores of species of mining bees but they are not very distinctive, being mainly small (mostly a few millimetres long) dark, furry insects, often with orange or brown hairs on their abdomens, hence the name of one of the most common - the tawny mining bee. The insects spend about a year underground as larvae and pupae before emerging as adult bees to start the cycle over again. This is where they become important to us. Just like honey bees they are valuable pollinators, seeking out the spring flowers, being especially fond of visiting orchard and hedgerow blossoms.
Mining bees suffer the attention of another group of bees which act like cuckoos in their nests. These are smooth, wasp-like insects which lay their eggs in the mines. When the eggs hatch the larvae first eat the mining bee larva and then feast on the nectar and pollen provided.
As well as natural enemies mining bees are just as susceptible to the effects of insecticides and other chemicals as honey bees. This is a good reason to minimise your use of such concoctions if you or your neighbours have apple, plum and other fruit trees. Your autumn fruit crop may depend upon these spring bees.