Gooseberry sawfly: how to recognise and treat it

Pest

Symptoms

Small holes in leaves low down in the centre of the bush, where the eggs are laid on the leaf undersides.
Caterpillar-like larvae up to 20 mm long, pale green with many black spots and black heads (some species have green heads), eating their way up and out.
Bushes are rapidly stripped of leaves, often to bare stems, from April to September in up to three generations.
Defoliated bushes rarely die but are weakened and may crop poorly the following year.

Pick off larvae by hand or shake the bush over a container; a strong jet of water also knocks many larvae off.
Water on pathogenic nematodes sold for sawfly larvae in cool, damp weather.
Spray insecticidal soap on young larvae.
Encourage birds, wasps and ground beetles, which eat the larvae.

Pyrethrins or spinosad on young larvae, only if larvae or damage are present; do not spray while bees are foraging, use a product approved for currants and gooseberries and follow the label dose and pre-harvest interval.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

From April inspect the centre of the bush for small holes in the leaves and tiny larvae, before a damaging population builds up.
Keep checking through summer — later generations appear in July and August–September.
Pick off heavily infested leaves and remove badly infested shoots.
Tolerate small numbers; complete defoliation rarely kills the bush.

Figures checked against these sources.