29-May May’s Miniature Dramas: London’s Insect Spectacles

May bugs are amongst the most formidable of all London’s insects. They have large, hard bodies, up to four centimetres in length. They are also noisy when they fly and have a habit of crashing into windows. This makes them quite intimidating and, when in swarms, terrifying. After two or three years underground as a larva, their adult life is relatively brief. They tend to fly in the evenings or at night and are a favourite food of bats. Other interesting beetles inhabit the leaves of water plants, particularly blue and green leaf beetles. Larger beetles seen this month are the rose chafer, dor beetle and tiger beetle. In ponds, the great diving beetle is common enough, but the great silver diving beetle up to five centimetres long, is much rarer although it does exist on Rainham marshes. Both can inflict a good bite, the latter with a sharp spine on its underside to help These, and other water beetles, fly at night from pond to pond.

Gardens are the domain of lily beetles. They are easily recognised due to their scarlet colour and preference for garden lilies. They only arrived sixty years ago and have already spread across the whole country. They sometimes make a slight clicking sound if touched and then instantly fall to the ground. The similar-looking and equally impressive cardinal beetle can still be found on Bookham Common. Soldier beetles, with their military precise parallel-folded wings and bright bronze, green and gold colours, are often to be seen on downland flowers.

Swarming mayflies have to be the insect highlight of the month. Mayflies are unusual in having two quite different adult forms, often referred to by fishermen as duns and spinners. The dun is first to emerge from the water and then often, after just a few hours and its last moult, it turns into the spinner. Several different mayflies can be found along the river Darent and watching them “dance” over the surface of the water can be quite mesmerising. The largest is the Greek Drake Ephemera danica which can reach three centimetres in length and has the typical upswept wings and three long tails of many other mayflies. It usually appears in the early afternoon and sometimes males form cloud columns by the water. They rise and fall looking for females occasionally diving to reach one. Once they have mated they often then fall to the ground or onto the surface of the water spout. Meanwhile the female continues to delicately lay batches of her eggs, occasionally touching the surface of the water as she does so. Once they are all laid she then meets the same watery end.

As many as a dozen or more other mayflies exist in the Darent some of which, especially the spinners, are quite colourful e.g. the Large Dark Olive Baetis rhodani, the Iron Blue Baetis muticus, the Sepia Dun Leptophlebia submarginata and the Yellow May Heptagenia sulphurea all of which are on the wing this month. The quieter, shady stretches of the river where there are beds of water crowfoot in flower e.g. near Shoreham, are good places to look.

Alderflies, which are far less flamboyant, are also emerging this month. In the River Darent they could well be Sialis fuliginosa. The adults are a shiny smoky-brown with darkly veined wings set tent-like on their backs when they are resting, as they often are on alder leaves overlooking the water. They are shy to fly and if encouraged to do so move quite awkwardly. Resting on leaves they often seem quite unconcerned by any human presence.

In similar habitats to mayflies, dragonflies and damsel flies are also now starting to be noticed more. In London, the broad-bodied chaser, four-spotted chaser, common blue damselfly, azure dragonfly, blue-tailed damselfly, red-eyed damselfly and black-tailed skimmer can all be seen this month. The large red dragonfly, although rare, is also a possibility.

On hot days, flies suddenly seem to be everywhere. The dance flies, fever flies, bluebottles, greenbottles and St Mark’s fly of last month are now joined by sawflies, gallflies, fruit flies and more hoverflies. Dance flies are sometimes recognised from their ghoulish habit of carrying the corpse of another fly. This enticing gift is then is laid in front of the female before the male mates with her as she feeds. Other noticeable insects this month include aphids, lacewings and shield bugs. A frightening ten million greenfly can inhabit a single London lime tree.

They are now rapidly increasing in numbers and on still, warm days they can occasionally form slow-moving clouds. Vivid lime-green lacewings, with their bright ruby or golden eyes may also be noticed flying badly. The adults have beautiful, shiny, lace-like wings, whereas some of their larvae have the habit of covering themselves with insect corpses to deter predators. Shield bugs often have boldly patterned shield-shaped wing cases. Some are common under the leaves of specific plants. Some show a rare feature among insects i.e. some degree of parental care. Females will sometimes even be seen covering their young with their shield to protect them. Cuckoo spit is also now commonly seen in gardens on plants such as lavender, the froth offering some protection for the soft, wet froghopper larva within.

Wherever there are a lot of insects, there will also be a lot of spiders. Orb, sheet and tangle webs are all now being constructed. Wolf, money and crab spiders are all hunting. Old grassland is always a good habitat to look for spiders, where jumping spiders may be seen leaping dramatically on their prey. More rarely, water spiders, on the surface meniscus of ponds, can be seen seizing their prey through the surface film.