Hornets hunting

Field Paintings

Our largest wasp the hornet Vespa crabro is an impressive insect and I always enjoy watching them hunt for insect prey in late summer. Clumps of flowering ivy are good places to find them. They will feed on the nectar but are much more interested in the other insects attracted to this autumnal feast. I spent several days in September and October this year watching them hunt around a farmyard ivy clump and around a patch of water mint in a wet meadow on the edge of Dartmoor.

The water mint patch was buzzing with insects, including dozens of bumblebees, hoverflies and small coppers. Worker hornets from a nest in a roof nearby occasionally appeared. They glowed orange in the slanting September light as they flew about slowly patrolling the flowers. Their tactic was to buzz any potential insects on the flowers but being less manoeuvrable than the smaller insects their hit rate was low. I also often saw them pounce on non prey items which resembled insects and spiders such as dead leaves and rush flowerheads. They were most successful catching their smaller cousins the common wasp Vespula vulgaris. Once caught the hornet would drop to the ground with its prey briefly then fly to some nearby vegetation and hang often by just one hind leg whilst it decapitated its prey. The wings and body were removed and the muscle rich thorax was then taken back to the nest.

For a few days newly-arrived immigrant silver y moths Autographa gamma swarmed over the mint and these attracted the attention of the hornets. I presume they must have been successful at times as they chased the moths persistently but I never saw them catch one.

Around the ivy they also targeted red admiral Vanessa atalanta. There were often several of these beautiful butterflies feeding together and a hornet would buzz around them in turn approaching head on. A quick flick of the wings in threat always drove the hornet away. It looked like the hornet was testing them for any sign of weakness. The same was the case with bumblebees though these frequently became victims. Often the hornet would drop to the concrete path below the ivy with a thud as it grappled with these large prey items.

Again common wasps and droneflies Eristalis tenax were frequent prey items with most being caught as the air cooled in the late afternoon and the prey were more sluggish. As the hornet season came to an end in late October several male hornets could be found hanging around the ivy. These could be easily recognised by their long curly antennae and longer slimmer bodies than the workers. As they don’t possess a sting it is possible to pick up the males to examine them but I always treble check first before doing this!

John Walters

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