Vine Weevil is a common pest that affects strawberries in Scotland. Here is what it looks like, how to spot the damage, and which controls have been tested.
What does it look like?
Adults: Weevil-type beetles about 9mm long, dull black with dirty yellow marks on the wing cases.
Larvae: Plump, C-shaped, white, legless larvae with light brown heads, up to 10mm long.
Is this pest active now?
Adults: Summer: leaf notching
Larvae (the damaging stage): Autumn to spring: root damage, and the lethal stage
Symptoms
Adults: Irregular-shaped notches in leaf margins during summer. Adults 'rarely cause enough damage to affect the vigour of plants'.
Larvae: RHS: 'Plants can wilt and die during autumn to spring as a result of the larvae devouring the roots.'
Life cycle
Adults notch leaves through summer; larvae devour roots from autumn to spring, which is when plants wilt and die.
Controls: what actually works
Every method below is graded by evidence, not by how often it gets repeated. Where a claim has been tested and failed, we say so plainly.
Biological control — pathogenic nematodes watered into the compost
Three nematode species are sold for this: Steinernema kraussei, Heterorhabditis megidis and H. bacteriophora.
Temperature ranges: Steinernema: 5-20C · Heterorhabditis: 12-20C
The two nematode species work at different soil temperatures. Steinernema species are active from 5-20C; Heterorhabditis species need 12-20C. Scottish soil rarely holds 12C for long: our parsnip guide records 12C as the gate that makes sowing late here, and our pea guide gives 10C. A Heterorhabditis product bought for a Scottish container in autumn, which is exactly when the larvae are eating the roots, is being applied below its working range. Steinernema kraussei, at 5-20C, is the species that actually functions in Scottish conditions.
Tolerate adult leaf notching
RHS: 'Adults rarely cause enough damage to affect the vigour of plants.' The notching is cosmetic.
But treat the notches as a warning: they mean adults are present and laying, and the larvae are the stage that kills. Tolerate the damage, act on the signal.
Frequently asked questions
What should I do first if I find vine weevil in my garden?
Start with biological control — pathogenic nematodes watered into the compost. After that, tolerate adult leaf notching. The full list of evidenced controls is above, each graded by how much evidence supports it.
Will vine weevil kill my plants?
They rarely kill established plants. The damage is usually cosmetic on outer leaves, and natural predators often bring numbers under control without you doing anything.
When are vine weevil most active in Scotland?
Adults are active Summer: leaf notching; larvae do the main damage Autumn to spring: root damage, and the lethal stage. Scottish timings may lag behind UK-generic advice, so use the Frost Date Calculator to adjust for your region.
Should I just leave vine weevil alone?
In most gardens, yes. vine weevil are food for birds, wasps and predatory insects, and a healthy garden carries some without trouble. Tolerance is also the official position now, and the stance box above sets out that reasoning in full.
Sources
1 source, recorded with what each was used for
- RHS1: widespread in Britain, adult and larval identification, leaf notching vs root destruction, container vulnerability, affected ground-grown plants including strawberries, three nematode species with temperature ranges, no pesticide recommendation