Nature on our doorsteps: Biological control
This red and black solitary wasp has the typical narrow waist of wasp species

Nature on our doorsteps: Biological control

Rosaleen Dwyer is the County Heritage Officer at South Dublin County Council – every week she gives us an insight into nature on our doorsteps and the beautiful biodiversity of its plants and wildlife.

THE STRIPY yellow and black wasp that we are most familiar with is only one of many thousands of wasp species across the world. Many are referred to as being social wasps, meaning that they live communally in hives or nests, just like honeybees and bumblebees.

The advantage of living together is that there are many workers around to help feed and care for the hive’s young.

Other wasp species, however, are solitary.

These do not live together in nests, and so they have had to evolve different ways of ensuring that the next generation has a safe place to grow and feed.

Some solitary wasps are parasitic and will lay their eggs in other insect species.

The females of these wasps lay their eggs in the caterpillars and larvae of flies, moths, and butterflies.

When the wasp’s egg hatches, the unwilling hosts become the home and the food for the developing wasp larvae.

This large solitary wasp has a black body and orange coloured legs

The caterpillar will die as a result of being parasitised. Some species of parasitic wasp lay their eggs on the surface of their chosen caterpillar.

These wasps inject a type of venom into the caterpillar which results in long-term paralysis of the caterpillar.

The venom also prevents the caterpillar from developing any further into the pupa or chrysalis form, so that it continues to be a source of food for the growing wasp larva.

Other female parasitic wasps lay the egg directly inside the caterpillar’s body using a pointed tube-like structure at the tip of their abdomen to pierce their prey.

They also use venom, which targets the caterpillar’s immunity and its nervous system.

While this entire process might appear very gory to us, it is an important balancing process in nature as it helps to control the number of caterpillars that graze on plants.

This natural, or biological, control is very important for us too, as these caterpillars can also be unwanted pests of agricultural crops.

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