Bees succeed against the odds, even when solitary.

By JW. Dowey - 18 Apr 2017 8:16:55 GMT
Bees succeed against the odds, even when solitary.

The ashy mining bee is quite common, and benefits from global warming as the species moves north, but how often do we notice these intrepid, quiet pollinators? Andrena cineraria image; Credit: © JW. Dowey

The solitary bees are not simply ignored. We are often totally unaware of their existence, even though they live on almost every continent. They fly in Spring, then hunker down under the ground and don’t emerge till the next Spring breeding season. You could say they are not like other bees. You could imagine they are an early experiment in social insectdom. They are very successful however in one respect. They pollinate the Spring fruit trees that we treasure so much. Every cherry and apple, plum and apricot has a few Andrena or similar bees sucking up the nectar, long before the hive bees have produced enough offspring to do the job. Small-scale works for this enterprise!

The European Andrena cineraria has its males emerge from their long-term tombs in April, followed by the females who of course are all queens, in the vernacular of the true social insects. Several other Palaearctic mining bees have a very similar life history, such as the willow mining bee in western N. America. There are other smaller species too, so it is worth keeping your eyes open for these tiny community workers.

The short existence of the males resembles other bee drones, but the females now dig short burrows, up to 20cm deep, near each other in well-drained areas, often in chalk, but also in clay or other areas. Before they lay their 2 or 3 eggs in individual cells, another bee often sneaks in to become the cuckoo in this nest. Numerous wasp-like Nomada bees specialise in parasitizing the mining bees, with great big larvae hatching from their own eggs to eat pollen, nectar and of course the resident, in the Andrena cells. Then, the next Spring, their successful enterprise often produces as many parasites as hosts from the neat little holes in the grass. The specific bee parasitising the ashy miner is Nomada lathburiana.

If all goes well with the ashy mining bee, the larva grows quickly, pupates, but remains in the cell till next Spring. Perhaps we can see potential evolution into a hive-like community in this species! The humble bees, for example, are large, very successful pollinators with similar niches.

The short life and heavy pressure of the Andrena mining bee resembles many others, but this larger and cheerfully-coloured species can represent them all for us. You can distinguish the head here quite easily from that of other bees. The hairs and velvety patch between the eyes, the very quiet buzz and that black and ash colour gives us a distinctive look, as well as those strange holes in your lawn.