You might remember that I recently wrote about some curious pea-sized holes that had appeared on one of my walking routes. It was the day after Warmageddon, the hottest day of the year, and I wondered whether it could be subterranean worms coming to the surface in a bid to escape the scorched earth surrounding them.

I was contacted by John Randles of Westerdale who thought they might have been made by a type of bee known locally as sand bees. A bank behind his house was littered with little holes and his friend said they were made by this bee. John also told me that sand bees will only emerge if the weather is just right. Too hot or too cold, it will keep to its burrow.

I tried to find out a bit more about sand bees, but could not find an insect of that name, neither in my dad’s books, nor on the internet. However, I did come across references to mining bees and so I am assuming that this is the species of bee in question. Reader Graeme Cunningham also suggested this after having some in his garden which lived in similar-sized holes.

Mining bees are solitary creatures, living alone in burrows beneath the ground, rather than in communal nests like their surface-dwelling relatives. You will spot if one has been active in your lawn if you see a small hole surrounded by a tiny volcano of earth. They are part of the Andrenidae subset of the bee family, of which there are 67 species in the UK.

The two most common are the tawny mining bee and the ashy mining bee, both of which are about the size of a honey bee, and not dissimilar in look and shape to a bumble bee. The female tawny bee is a beautiful wee thing, with black head and legs contrasting sharply against a sunset orange tail and thorax (the bit between the head and tail). Its male counterpart is smaller, and brownish in colour. The female will build her nest where grass is cut short, or in areas of bare soil. They fly between March and June and their favourite flowers include buttercups, dandelions and fruit tree blossom.

The ashy mining bee is distinctive by its monochrome colouring. It is mostly black, but with two grey stripes on its back. It adapts well to different habitats, and as it can be found in moorland and coastal areas, I wonder if this is what John Randles’ friend calls the ‘sand bee’?

It is a bit cleverer than its orange cousin though, in that it uses the excavated earth from building its nest to cover up the hole again, protecting it from rain and from deadly enemies. It can be seen flying from April to August, and you are most likely to spot them on willow, blackthorn, gorse, buttercups and fruit tree flowers.

Mining bees have a dastardly predator in the greater bee-fly. As the name suggests, it resembles a fluffy orangey-brown bee and its innocuous appearance means its prey mistake it for a benevolent relative. It is noticeable in the garden because it can be seen hovering in the same place for an unusually long time. That is because it will have spotted the entrance to a mining bee nest and is waiting for it to leave. Once the coast is clear, the devilish bee-fly will swoop in to deposit its eggs in the nest which, when hatched, will eat whatever is immediately available, such as the resident’s hard-earned pollen and its poor wee tawny bee babies.

It is also possible that the ‘sand bee’ is a type of wasp. Known as the ‘digger wasp’, their behaviour and nesting habits are very similar to the mining bee. The main difference, apart from the waspy appearance, is the fact that they are carnivores. They catch their prey by stinging them, which immobilises them, and then carry them home to devour. It’s not uncommon to see a digger wasp dragging a paralysed caterpillar twice its size.

The two main species in the UK are the field digger wasp and the sand digger wasp, and I think you can work out why they are so-named. This wasp particularly likes building its nest in steep, barren, banks, so is John Randles’ sand bee not a bee at all, but a wasp?

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