Wasps earn their stripes killing pests

Wasps earn their stripes killing pests

Wasps earn their stripes killing pests

First published in News by

Val Bourne on why this insect is a friend, not a foe

Go into any garden centre and you will spot wasp traps of one sort or another and that’s rather sad — for the wasp is definitely the gardener’s friend and therefore should be encouraged.

For most of its life, it’s a meat-collecting creature and pollinator. It’s the only creature I’ve ever seen tackle a large cabbage white caterpillar for when these get larger, their bodies are full of bitter mustard oil, ingested from various brassicas, and even my chickens won’t touch them. The wasp will happily collect them, working in small teams they cut the fat caterpillars into sections of liftable size and fly away with them. It’s fascinating to watch them. At other times they collect grubs and small insects, again to take back to the nest. They manage this amazing feat due to their sting: they immobilise their prey with it.

Last year I had a nest in my roof and, as I don’t have an attic, I decided to ride out the situation and leave the spare bedroom window open and let them get on with it.

This year I was braced for the same problem, but this year there’s a nest (pictured) in an unpruned cherry laurel hedge instead. It’s a wonderful cone-shaped construction and my wooden gates have had slithers of wood cut from them — in order to build that nest. The wasp saliva and wood form a paper-like substance. This nest is conical and I am unsure whether it’s the common wasp (Vespula vulgaris) or another. We also have some darker wasps in the garden. Apparently hoverflies also use the nests, although I am unclear about how (see Buglife at www.buglife.org.uk) In Britain, we have 250 species of wasp and most of them are tiny solitary species, not social nest-builders. The common wasp, pictured here on a marigold, is yellow and black. Adult workers, which are always female) measure 12-17mm and the iconic black-and-yellow stripes give a clear warning to other animals that these insects are dangerous. The abdomen is split into six segments, one black and yellow stripe on each.

The Common wasp is very similar to the German wasp (Vespula germanica). The key difference being that Common wasps lack the three black dots on the head and distinct black dots on the back that merge with the back stripes.

In summer smaller social wasps gather protein to feed the larvae, ridding the garden of pests and probably some predators as well. Currently my wasps are more interested in pollinating my autumn raspberries, probably due to a late start following our wet spring. The queen will be focusing on reproduction and a successful nest may contain 5,000-10,000 individuals.

In late summer new queens and male drones emerge from the nest. These new queens, always larger than workers, overwinter in holes or other sheltered locations and then emerge in spring.

Once the new queens depart, all the other wasps in the colony die. It is this gradual decline in numbers that causes the wasp to develop a sweet tooth, for with fewer larvae to gather insects for they begin to binge on sugar.

In my garden they are very attracted to a red hot poker, Kniphofia ‘Prince Igor’. Knock against this now and nectar splashes down your arm on a warm day. That supply of garden nectar seems to prevent them from coming into the kitchen, even when I am making plum jam. We also get parasatic wasps and very scary wood wasps, with long tails. Although menacing to look at, wood wasps do not sting, they are mimicking being scary to protect themselves.

Wasps have a bad name. However if you’re a natural gardener like me, who uses no sprays, they are a vital part of pest control.

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