27-July Hive Minds: London’s Social Insects Uncovered

A larger very active dull black ant found in woodland could well be the Dusky ant Formica fusca. These ants are occasionally made into slaves by the similar-sized blood-red or slave-maker ant F. sanguinea which has a bright red thorax. It raids nests taking away larvae and pupae to raise as its own resulting in two different workers being present in the same nest. Another medium-sized black ant found in London woodland is the jet black ant Lasius fuliginosus which can be recognised by its heart-shaped head and yellowish legs. It likes nesting in tree stumps as does another common similar-sized red or fire ant Myrmica ruginodis. This last ant is one that usually prefers to stand and fight an intruder, spraying it with formic acid rather than running away.

In meadows such as those at Quarry Hangers near Merstham many small ant hills can be seen close together yet so evenly spread it might suggest the ants of one hill are trying to avoid another. These are home to a small yellow ant Lasius flavus. There is only one queen in each ant hill but perhaps as many as a quarter of a million workers attending her. We see very little of them as they spend most of their life underground. These ants like many others take aphids into their nests to milk them for their sugary honeydew. On Denbies hillside they have a similarly symbiotic relationship with the larvae of chalkhill blue butterflies.

There are several other ants to be found in London that are often quite difficult to identify. For the keen observer eight different species can be found on Mitcham Common including Myrmica sabuleti, M. scabrinodis, M. schencki, and Formica canicularia. Yeading Brook meadows has five different species including the yellow lawn ant Lasius umbratus, the brown tree ant L. brunneus and other fire ant Myrmica rubra.

Among the large number of bees around now there are a number of interesting solitary species worth looking out for. Wool carder bees can sometimes be seen collecting their ‘wool’ from the leaves of mulleins in the wild and lamb’s ear Stachys lanata in gardens. They make a woollen ball sometimes almost bigger than themselves, before carrying it off to line their nest. They are black, almost hairless bees, with brownish-yellow edges to their abdomens. Other carder bees are more brownish.

Leaf-cutter bees may also be noticed cutting semi-circular pieces out of rose leaves. These are then taken to their nests to build tunnels and cells. The bees themselves are often large and solid-looking, usually black or dark brown with some yellow markings. With their large heads and powerful jaws they are also known to cut other leaves such as lilac, sunflower, laburnum and willow. Each egg is laid in turn in its leaf cell. The males are always the first to emerge and wait nearby for the females to follow them.

Yellow-faced bees are also to be seen this month. They tend to look like shiny black wasps that behave like bees. Some have yellow markings on their faces. Their small nests are constructed in the hollow stems of plants.

It is now also the time when several different wasps start to be noticed. It is always wiser to look for wasps when the sun is shining as this is when they are most active. They tend to rest a lot if it is cloudy.

Mason wasps are often noticed around small, neat holes in brickwork. Sometimes, small writhing caterpillars are seen on the ground nearby. These will have been partially paralysed by the wasps before they get carried back to the nest. The nest itself is usually down a hole in the mortar and will already be furnished with other paralysed caterpillars. When enough have been collected, the female then lays an egg suspended in each cell. When these hatch, they will have enough live food to eat to last them through the whole of their pupation although it will not be until next year that the new adults will emerge. Near such nests, it is always worth looking out for ruby-tailed wasps. These are parasitic wasps that tend to hang around watching the activities of mason wasps. At the moment the female mason wasp goes to seal her cells, the ruby-tailed wasp intervenes and lays one of her own eggs in the cell. When this hatches, it not only eats the mason wasp egg, but also any larvae present.

The body of one common species Chrysis ignite is a very noticeable iridescent ruby red. Its head and thorax are a metallic green and purple and its dimpled surface sometimes has a golden sheen. Others have different mixtures of all those eye-catching colours and lustres.

Yet another group of solitary wasps are the digger wasps. They are mostly reddish-black or reddish-brown, with long, slender bodies and long, thin waists. They have similar habits to mason wasps, but choose to fill their nests with paralysed flies in the sandy areas that they prefer.

Spider-hunting wasps do much the same but they catch spiders instead and tend to have longer legs for the task. It is usually the beautifully constructed ‘pots’ on heather stems that announce the presence of potter wasps. The wasps themselves have distinctly curved abdomens and also collect and paralyse caterpillars in this case to store in their ‘pots’. If the wasp seen has a black tip to its orange abdomen, it could well be a sand wasp. Like many other solitary wasps, they are seen on sandy heaths, in this case dragging a paralysed caterpillar along the ground again to bury it beside one of its eggs in a burrow

Hornets are our largest British wasps with a correspondingly frighteningly loud hum. They are easily distinguished by their sheer size and brown and orange markings, rather than the usual sulphur and black. Although fearsome-looking, their bad reputation is largely underserved. They tend to be docile creatures, rarely stinging humans. They are, however, formidable predators of other insects, thinking nothing of taking on butterflies, dragonflies or even other wasps. Although armed with a powerful sting, they prefer to bite off the head of their victims.

Lastly, going largely unnoticed, are the tiny, dull-coloured gall wasps such as the oak apple gall wasp Biorhiza pallida. These adults are now emerging in vast numbers from oak apples all over London. A good place to look for different wasps and bees is Hounslow Heath, where over one hundred different species have been recorded.