Gooseberry Sawfly is a common pest that affects gooseberries and redcurrants.
What does it look like?
The larva gives the pest away: caterpillar-like and pale green with many black spots and a black head, up to 20mm long in the common species. The pale spotted species is slightly smaller with pale green heads. Adults are small sawflies and rarely noticed: the common female is 5 to 7mm, yellow with a black head and black markings on the thorax, and the small gooseberry sawfly is about 5mm, black with pale yellow legs. Gooseberry, red currant and white currant leaves are all eaten; blackcurrants are not named as hosts (RHS).
What causes it
Eggs are laid in clusters on the underside of leaves, low down in the centre of the bush and out of easy sight, so the first generation of larvae can already be feeding well before damage shows on the outer foliage. A check that only covers the outside of the bush misses where the pest starts.
Is this pest active now?
Watch from April through September, the full window across all three species' overlapping generations.
🌱 Plants at risk
Symptoms
Larvae eat their way upward and outward from where the eggs were laid, and foliage is devoured quickly, so a bush can go from a few holes to heavy leaf loss between checks. Bushes usually survive complete defoliation, but a stripped bush is weakened and may crop less that year and produce a poor crop the following year.
Life cycle
How many generations a bush faces in a season depends on the species: the common gooseberry sawfly runs three, active late April to June, then July, then August to September; the small gooseberry sawfly can run up to four from late April onward; the pale spotted species has just one, in May and June. All three pupate in cocoons in the soil.
Why this matters in Scotland
No Scottish records, incidence figures or timing were found for gooseberry sawfly, so the UK dates are the guide: start checking in April.
A bush stripped early in the season has less time to recover before the next generation arrives, which is why the checks run through to September.
Controls: what works
Not every method here works equally well: some are backed by real evidence, others are simply traditional and untested.
Check bushes regularly from April, starting at the centre of the bush
Start at the centre of the bush and look at the underside of the leaves, where the eggs are laid. Leaves further out stay clean longer, so waiting to spot damage there means the first generation is already well established. Garden Organic suggests searching twice a week through the season.
Hand-pick larvae and destroy them
Picking off and destroying larvae as soon as they're found stops a small early problem becoming a stripped bush, and needs nothing beyond the regular check. Squashing clusters of eggs or young larvae on the leaf undersides in spring and early summer prevents a large infestation.
Biological control: pathogenic nematodes watered into the soil
Pathogenic nematodes are watered on in cool, damp weather; they enter the larvae and infect them with a bacterial disease. They can infect non-target animals, so use them with care and only when there is a specific problem to treat. Worth considering where hand-picking alone isn't keeping up.
Clear debris and lightly rake or hoe the soil under the bush
Many sawfly larvae overwinterKeeping a plant alive and intact through the cold months, whether left outdoors, moved under cover, or stored dormant. Full definition → in the soil under their host plant, and disturbing it exposes them to frost and birds. This is general sawfly advice rather than a test on gooseberry sawfly, and it is a supporting measure alongside the checks, not a replacement for them.
Myths about gooseberry sawfly
“Gooseberry sawfly is a gooseberry-only pest and doesn't touch currant bushes.”
The RHS and Washington State University's extension service (US) both list currants alongside gooseberries as hosts. The RHS pest page names gooseberry, red and white currants, and its redcurrant growing page lists gooseberry sawfly among common problems. Blackcurrants are not named as hosts on the RHS pest page, so a safer version of the myth is that it skips blackcurrants.
Our read Treating currants as one category is what breaks the claim: redcurrants and white currants are hosts.
What to do: Put redcurrant and white currant bushes on the same twice-weekly check as gooseberries; blackcurrants don't need watching for this particular pest.
2 sources
- RHS, Gooseberry SawflyGooseberry sawfly larvae feed on gooseberry, red currant and white currant leaves.
- Washington State University Hortsense, Currant, Gooseberry: Imported CurrantwormThe pest targets currants and gooseberries, laying eggs on the underside of leaves near the midrib.
“Hand-picking sawfly larvae doesn't work because they hide low down inside the bush where you can't see them.”
Eggs are laid on the underside of leaves low down in the centre of the bush, and both the RHS and Garden Organic still recommend hand-picking. Garden Organic's advice is to start the search in the centre of the bush and work outwards, not to scan the outer foliage first.
Our read This myth gets the biology right and the conclusion wrong. Knowing where the larvae hide is what makes hand-picking work, not what defeats it.
What to do: Start every check at the centre of the bush and the underside of the leaves, then work outward, rather than glancing over the outer foliage and assuming the bush is clean.
2 sources
- RHS, Gooseberry SawflyFemale sawflies lay eggs on the underside of leaves low down in the centre of the bush, so young larvae go unnoticed until they've eaten their way upwards and outwards.
- Garden Organic, Your Organic Garden in JulyContinue a twice-weekly search for gooseberry sawfly larvae, starting in the centre of the bush and working outwards, and pick off and destroy what you find.
“A bush stripped completely bare by sawfly larvae is dead or as good as dead.”
Plants will usually survive complete defoliation, though yield may be reduced, and defoliated plants are weakened and may produce a poor crop the following year. The bush itself is not lost.
What to do: Don't dig out a defoliated bush. Focus instead on catching the next generation of larvae early so the same bush doesn't get stripped a second time in one season.
1 source
- RHS, Gooseberry SawflyPlants will usually survive complete defoliation, however this may reduce yield.
“Once you've dealt with a gooseberry sawfly outbreak, that's the pest sorted for the season.”
The common gooseberry sawfly has three generations a year, with larvae active late April to June, in July, and in August to September, and the small gooseberry sawfly can have up to four. Washington State University's extension service (US) notes a second generation appearing around June or July. A bush cleared in May can still face a fresh wave of larvae in high summer and again into early autumn.
What to do: Keep the twice-weekly check running from April through September, not just for as long as it takes to clear the first generation.
In Scotland: No Scottish dates were found; the RHS generations are UK-wide. A bush stripped in May has less time to recover before the next generation, which is why the checks run through to September.
2 sources
- RHS, Gooseberry SawflyThe common gooseberry sawfly runs three generations a year, active late April to June, then July, then August to September; the small gooseberry sawfly can run up to four.
- Washington State University Hortsense, Currant, Gooseberry: Imported CurrantwormTwo generations are possible in a season, with the second appearing around June or July.
“A healthy gooseberry bush can go from a few nibbled leaves to completely bare in just a few days once sawfly larvae get going.”
The caterpillar-like larvae devour foliage rapidly, and once a population is established on currant and gooseberry leaves they can cause severe defoliation. Eggs are laid on leaf undersides low in the centre of the bush, so damage that looks minor from the outside can already be well advanced.
Our read Neither source gives a number of days, but rapid feeding and eggs hidden low in the centre are why a bush can look fine at one visit and stripped by the next.
What to do: Check bushes twice a week from April, starting at the centre of the bush, so a small cluster gets picked off before it becomes a stripped bush.
2 sources
- RHS, Gooseberry SawflyFoliage is rapidly devoured by the caterpillar-like larvae once they hatch.
- Washington State University Hortsense, Currant, Gooseberry: Imported CurrantwormLarvae feeding along the leaf margins can cause severe defoliation of currant and gooseberry bushes.
Frequently asked questions
What should I do first if I find gooseberry sawfly in my garden?
The first thing to try: Check bushes regularly from April, starting at the centre of the bush. Then: Hand-pick larvae and destroy them.
Will gooseberry sawfly kill my plants?
Not usually. Bushes normally survive complete defoliation, but it weakens them and can reduce that year's crop and the following year's.
When should I watch for gooseberry sawfly?
Watch from April through September, the full window across all three species' overlapping generations.
Should I just leave gooseberry sawfly alone?
Often, yes. A light attack can be tolerated, and birds, wasps and ground beetles eat the larvae. Step in by hand-picking if a bush is being stripped.
Sources
Show the 6 sources
- RHS1: identification, symptoms, the centre-of-bush egg-laying trigger, life cycle and generations by species, monitoring, hand-picking, nematode drench, encouraging predators, tolerance framing, absence of a chemical control
- RHS1: confirming gooseberry sawfly directly on gooseberries' own growing page
- RHS1: confirming gooseberry sawfly directly on redcurrants' own growing page
- RHS1: confirming blackcurrants' own growing page does not name this pest, supporting its exclusion from affected_crops
- Garden Organic8: twice-weekly monitoring frequency and starting point, and hand-picking
- Gardener's World7: no real need to combat sawflies, chemicals also kill bees and butterflies, squashing eggs and young larvae, clearing debris and raking the soil, birds, wasps and ground beetles as predators