Vine Weevil Control
- Common names: Vine Weevil (Black Vine Weevil / Garden Weevil)
- Scientific name: Otiorhynchus sulcatus
- Areas affected: Ornamental plant borders, container plants, fruit bushes, nursery-grown plants
- Plants affected: Over 200 plant species (euonymus), plus many weeds (dandelions)
- Main symptoms: Lack of vigour, wilting (larvae root damage), leaf notching, serrated leaf edges (adult beetle damage)
- Most active: Larvae: summer to spring. Adult weevils: spring to late summer
Vine weevils are the most common problem encountered by growers & plant nurseries. They are a well-adapted pest and have several clever tricks to ensure their survival in plant pots and in open soil of plant border and gardens.
Life Cycle: This can last between 9-11 months:
- Adult vine weevil beetles lay up-to 300 eggs at a time in the top 5 cm of soil when conditions are right. If they have survived a mild winter they will lay eggs from April, but weevils that emerge in May/June will lay eggs from July onwards up until November if temperatures are still mild
- After 10-14 days at 20 degree Celsius, eggs hatch into grubs (larvae) – 10-12 mm long, white bodies with brown heads – curled into a ‘C’ shape
- Grubs feed on plant roots and stem cambium below soil level
- Larvae will feed till October, dive deep for winter then start feeding again in spring when soil temperatures are warm enough. The grubs then pupate into Adult weevils around April/ May. These are black/ grey and cannot fly
- Adult weevils can live for many months. They reproduce via parthenogenesis which means that each weevil itself can produce and lay up-to 1600 eggs in a good (warm) year.
Weevils will happily munch the leaves of over 200 plant species – the most common being Camelia, Rhododendron, Euonymus & Primula – while the grubs can hide in the soil and especially enjoy the roots of Heuchera. Weeds will also provide shelter and food for grubs & weevils, commonly: dandelions, dock, Rosebay Willowherb.
Once they find a source of nutrition weevils tend not to move very far (0.5 m) unless the plant begins to suffer or food runs out
Weevils feed at night. They play dead in bright light so use dim light from torches to check vulnerable plant species. Its also very useful to use monitoring traps both to gauge activity, time treatment plus get rid of a few pesky egg-laying weevils. – this can be done DIY by burying a jar fully up to the neck and use jelly or grease to stop the adults crawling out. Cover the jar with a ‘cap’ made from a plastic drinks bottle cut halfway down and with little doors cut into the cut rim to allow weevils to walk under the cover and fall into the jar without water filling it up.
Vine Weevil Treatment Options:
Larvae control - using Nematode worms
A non-pesticidal treatment for larvae infested pots and soil. They are a very effective vine weevil killer, using biological pest control. Microscopic worms to go out and actively hunt down vine weevil larvae / vine weevil grubs by following CO2 vapours in the soil from their movements.
There are pack sizes suitable for amateur and professional growers containing millions of Heterorhabditis bacteriophora and Steinernema feltiae nematodes to cover 100 m2, 500 m2 or 1000 m2. These natural non-pesticide alternatives are completely safe to humans and pets with no exclusion period after application.
Product: Seeka is our recommended product for Nematodes to control Vine Weevil.
Correct soil temperatures should be measured accurately by using a soil probe thermometer