• Severe defoliation of the bushes can be caused by the caterpillar-like larvae of one of three species of sawfly
• Larvae of the common gooseberry sawfly are up to 20mm (almost ¾in) long, pale green, with many black spots, and black heads  The adults are winged insects;  females are 5-7mm (up to ¼in) long and are yellow with black heads and black markings on the thorax; males are similar but more extensively marked with black, including the upper surface of the abdomen
• Larvae of the pale spotted gooseberry sawfly are slightly smaller than those of the common gooseberry sawfly and have pale green heads. It has one generation a year with larvae present in May and June
• The small gooseberry sawfly can have up to four generations of pale green larvae from late April onwards
• The larvae of some moths may also eat the foliage of gooseberries and currants

Non-chemical control

• Regularly check the plants from mid-April onwards for sawfly larvae and pick them off by hand
• A biological control (pathogenic nematode), sold as Fruit and Vegetable Protection, can be watered onto infested plants. The nematodes enter the bodies of the sawfly larvae and infect them with a bacterial disease. This nematode is available from some garden centres or via mail order. The nematode should be applied during cool damp weather

Chemical control

• Spray when young larvae are seen, with an insecticide approved for use on the appropriate food plant. Make sure that the manufacturer’s instructions regarding maximum number of applications and harvest interval are followed
• Suitable insecticides include the contact pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Bayer Provado Ultimate Fruit & Vegetable Bug Killer) or an organic pesticide such as pyrethrum (e.g. Defenders Bug Killer)
• Plants in flower should not be sprayed due to the danger to pollinating insects
• Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biological control suppliers (Abode Acrobat pdf)

• The common gooseberry sawfly is the most troublesome pest of gooseberries. It can have three generations a year, with the larvae active in late April to June, July, and August to September
• The female sawflies lay eggs on the underside of leaves, low down in the centre of the bush, so the young larvae go unnoticed until they have eaten their way upwards and outwards, devouring the leaves as they go
• Defoliated plants are weakened and may produce a poor crop the following year
• When the larvae are fully fed, they go into the soil, where they spin silk cocoons and pupate
• The pale spotted gooseberry sawfly only has one generation a year with larvae present in May and June
• The small gooseberry sawfly has up to four generations a year with larvae present from late April
  

  ---