Nature on our doorsteps: The Gooseberry Sawfly

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.

SAWFLIES are a large group of insects related to wasps, bees and ants.

Their name arises from the egg-laying tube that occurs at the tip of the female’s body, which she uses to cut into plant tissue to lay her eggs.

Anyone who has tried to grow gooseberry bushes will most likely know the Gooseberry Sawfly, although this general name is often applied to three related Sawfly species.

Adults of these Gooseberry Sawflies are not very noticeable.

They are weak fliers, with yellow-brown bodies and with see-through wings which are held folded over their backs.

Gooseberry Sawfly adults are easy to overlook amongst the leaves

In early spring, the female lays her eggs near a vein on the underside of newly growing gooseberry leaves.

The hatched larvae initially look like tiny green caterpillars.

They stay together as a group, and quickly begin to devour every leaf around them until they strip the stem.

The larvae shed their skins a number of times as they grow, changing their body colour from the initial bright green to a lighter shade of grey-green, with raised black spots.

A narrow band of yellow occurs behind the head and close to the ‘tail’ end.

These larvae have a distinctive way of curling the end of their body into a loop as they feed and rest.

While the larvae can strip stems bare, the plant itself does not appear to suffer too badly.

Once the mature larvae have moved down the bush into the soil where they develop further into the adult form, the Gooseberry bush usually recovers and sends out new leaves.

Sawfly numbers are often controlled naturally.

The larvae are a very important food source for birds and their chicks in early summer, and they are also targeted by parasitoid wasps who lay their eggs inside the larvae.

The unfortunate larva then becomes a wasp nursey, where the wasp’s larvae grow and develop by feeding on the insides of the Sawfly caterpillar.