I was fortunate to observe at close quarters just how successful a predator is the common wasp.
My conservatory attracts numerous small hoverflies. Many venture in through open windows while feeding on flowers in the garden, congregating below the ceiling. Once inside, they seem incapable of flying back out again — so dozens become trapped.
I watched in July as a wasp flew in, zigzagged around near the ceiling then suddenly made a ‘beeline’ to a hoverfly which it seized in mid-air. Both insects became locked together with a frantic buzzing, plummeting to the floor whereupon the wasp bending double to clasp its capture proceeded to dismember the hapless hoverfly — first the wings, then legs and head were bitten off and discarded.
Thorax and abdomen were then kneaded and pre-masticated into an easily transportable bundle before the wasp flew out and headed off to its nest.
The whole episode lasted just three minutes. The wasp was back five minutes later to stage a repeat and during the next hour seven hoverflies met an untimely end in my conservatory!
Every day for the following two weeks the wasp commenced operations just after first light and complete its last sortie as dusk fell. Assuming the success rate remained constant, simple maths suggests that on an average day in wet or sunny weather that same wasp accounted for 80 or so hoverflies!
I went on holiday during the first two weeks in August and locked the windows.
I opened up again on my return and within seven minutes several hoverflies drifted in. Half-an-hour later the wasp returned to begin its depredations and was swiftly joined by a second wasp that had clearly got the message.
Previously, it had initially discovered the rich harvest purely by chance. The trick was remembered for more than two weeks.
Sometimes the two wasps prepared their food parcels on the floor or on other occasions beneath the ceiling from which point hoverfly legs, head and wings would flutter down.
It was interesting to note that following a phase during which both thorax and abdomen were carried off, the feeding pattern changed, the wasps contending with just the thorax.
I didn’t mark either wasp, but am convinced that the same two individuals were involved.
It became apparent that the wasps did not catch sight of their prey at distances greater than 15 centimetres and only if facing directly at the target.
From late August, as hoverfly activity lessened, wasp visits became less frequent and lacked the urgency — due probably to the fact that larval mouths were fewer to feed as nests reached maturity and ceased completely at the end of August.
For me, time spent observing their timeless behaviour was rewarding and I soon developed a healthy respect for the much maligned wasp.
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