Q What is gooseberry sawfly?
A Gooseberry sawfly is a common gooseberry pest. It’s the larvae that do the damage.
Caption: Gooseberry sawfly larvae will quickly strip the leaves
Q How do I recognise gooseberry sawfly?
A Sawfly larvae look similar to caterpillars, but they have shinier skins and, in addition to the three pairs of legs at the front, each other segment of the body has a pair of fleshy pro-legs. They are pale green and grow up to 20mm long; two species are covered with small, black spots.
Three species of sawfly affect gooseberries: gooseberry sawfly (Nematus ribesii); pale gooseberry sawfly (Pristiphora pallipes) and lesser gooseberry sawfly (N. leucotrochus).
Q Can you tell me more about gooseberry sawfly?
A Overwintering pupae hatch in April and lay eggs on the young leaves in rows parallel to the main vein. The larvae feed voraciously for about a month, and then pupate. The flies emerge three weeks later. Each year two or three generations develop.
Q What damage do gooseberry sawfly do?
A The sawfly larvae eat their way through the leaves from the edge inwards, often leaving the midrib. When they occur in large numbers they are able to defoliate a bush within a week. The fruit is not affected, but the loss of a significant number of leaves will lessen the vigour of the bush and may reduce fruiting the following year.
Q Will gooseberry sawfly attack other plants?
A Gooseberry sawfly also attacks red- and whitecurrants, and a close relation feeds on blackcurrants.
Q How can I control gooseberry sawfly?
A Check bushes regularly. Eggs are often laid low down in the centre of the bush, so it's easy to miss the larvae until lots of damage has been done. The simplest control is to pick off the larvae by hand.
Alternatively, use an insecticide approved for fruit such as Provado Ultimate Bug Killer or Westland Plant Rescue for Fruit and Veg or an insecticide based on pyrethrum such as Scotts BugClear Gun! For Fruit and Veg or PY Garden Insect Killer.
The biological control Nemasys Grow Your Own contains minute nematodes that enter the caterpillars and kill them.
Even after controlling an outbreak, keep checking the bushes, as surviving larvae will become adults in a few weeks, ready to start the life cycle again.