Vine Weevil
Overview
Vine weevil is one of the most economically important root-feeding pests in protected horticulture and container production.
It is especially problematic in:
- substrate-grown strawberries
- ornamentals
- nursery crops
- container systems
- propagation systems
- long-season protected crops
The pest causes damage in two distinct stages:
- adults feed on foliage
- larvae feed on roots and crowns
Larval feeding is the most damaging stage and can rapidly destroy root systems in container-grown crops.
Identification
Adult vine weevil
Adults are:
- black or dark brown beetles
- approximately 8–10 mm long
- flightless
- mainly nocturnal
- slow moving
Typical adult damage: - notching around leaf edges - scalloped feeding marks - cosmetic leaf damage
Adult feeding is often the first visible warning sign.
Larvae
Larvae are:
- creamy white grubs
- legless
- curved “C-shape”
- brown-headed
Usually found: - around roots - in crowns - within substrate - beneath the plant
Larvae are responsible for the most serious damage.
Life cycle
Adult females lay eggs within growing media or substrate.
Typical cycle:
| Stage | Approximate timing |
|---|---|
| Eggs | 1–3 weeks |
| Larvae | Several weeks to months |
| Pupae | 2–4 weeks |
| Adults | Long-lived |
Protected crops may allow overlapping generations.
Larval pressure often increases: - late summer - autumn - mild winter periods in protected systems
Damage symptoms
Adult feeding
Adult damage includes: - leaf notching - scalloped edges - cosmetic foliage damage
Adult feeding alone is rarely economically serious.
Larval feeding
Larvae damage: - roots - crowns - root hairs - stem bases
Symptoms may include: - wilting - poor rooting - stunting - collapse - sudden plant death
In strawberries: - weak crowns - poor vigour - collapse during stress periods
Conditions favouring vine weevil
| Condition | Risk effect |
|---|---|
| Container production | Very High |
| Coir/peat substrates | High |
| Long-season crops | High |
| Dense protected systems | Moderate–High |
| Poor substrate inspections | High |
| Carryover trays/pots | High |
| Warm protected conditions | Moderate–High |
Monitoring
Adult monitoring
Inspect: - leaf notching - bench edges - beneath pots - night activity
Adults are most active at night.
Night torch inspections can be highly effective.
Root inspections
Inspect: - weak plants - root zones - crowns - substrate around roots
Look for: - larvae - root feeding - crown damage
High-risk areas
Pay particular attention to: - old stock plants - carryover trays - propagation areas - long-term container crops - sheltered warm zones
Biological control
Vine weevil is usually managed using integrated biological approaches.
Beneficial nematodes
Entomopathogenic nematodes are commonly used against larvae.
Most effective when: - substrate moisture is suitable - temperatures are appropriate - applications are timed correctly - larval populations are not excessive
Preventative applications are usually more effective than rescue treatments.
Environmental management
Useful practices include: - removing old substrate - cleaning trays and pots - reducing carryover plants - monitoring stock plants - avoiding hidden reservoirs
Propagation and nursery risk
Propagation and nursery systems are especially vulnerable because:
- crops remain containerised for long periods
- roots are concentrated
- substrate movement spreads pests
- old trays and pots act as reservoirs
Infestations may spread silently between batches.
Common hotspot areas
High-risk areas include:
- beneath benches
- stock plant areas
- old pots and trays
- propagation tunnels
- sheltered container zones
- carryover crops
Practical IPM strategy
Strong vine weevil programmes usually combine:
- preventative nematodes
- substrate inspections
- hygiene
- stock plant monitoring
- tray/pot sanitation
- removal of weak plants
- prevention of carryover reservoirs
Biological control is usually most successful before heavy larval populations develop.
Commonly affected crops
Vine weevil is especially important in:
Related BioWiki pages
Key message
Vine weevil problems are usually discovered after larval root damage has already become severe.
The strongest programmes focus on: - prevention - substrate hygiene - early root inspections - preventative biological control - elimination of carryover reservoirs