Vine Weevil Control - Nematodes

Vine Weevils are a real double whammy for gardeners...the grubs or larvae eat the roots, and the adult eats the leaves!  The damage is distinct from slug and snail damage as they bite the edge of the leaves rather than making holes in the middle.

Adult Vine Weevils are black beetles about 8mm long with the front part narrower than the back, so that they look as if they have a long nose, or snout. It is important to look for this feature, because otherwise they can be confused with ground beetles, which are a gardener's friend. If you see bitten edges around the leaves of your plants, then suspect vine weevil. To see them in numbers you will need to take a torch and go out at night-time into the garden and search among the leaves.

The adult feeds at night on leaves, making unsightly notches around the edges, hiding during the day. During the period from June to August you may still be plagued by the adult beetles. We sell a trap for the adults, more details on this here.

Some gardeners go out at night, and lay out a sheet underneath their most vulnerable shrubs or plants. Then they shake the shrub to tip the beetles onto the sheet, gather up the sheet, and dispose of the beetles. One tip is to sprinkle a thick layer of grit around plants at risk to deter egg-laying adults.

Vine Weevil Grubs

Eggs are laid near the plant stems in the summer and they hatch into white, horseshoe shaped grubs which stay in the ground during summer and autumn and winter and only emerge into adults the following year - typically early June. Vine Weevil larvae are ugly-looking grubs which feast on plant roots, often completely severing them from the upper stems. You can recognise them by their soft creamy-white body, up to 1.5 cm (half inch) long and their brown heads. They often lie in a sort of "C" shape.

Life Cycle: Adults typically emerge in June, start laying eggs in July through into the Autumn, but are typically killed by winter frosts. By that time the eggs have produced larvae (August) and these larvae feast on roots below ground until winter, when they dig in deep below the frosty soil, and hibernate until spring. As soon as the soil gets warmer (March-May), they start feeding again, and then pupate in May/June, to release a new set of egg-laying adults.

Vine weevil nematodes come in packs of 12 or 100 square metres and should be used every 6 weeks from the spring into autumn.

The two most important treatments are the first and last treatments in the season. March when they have emerged from their winter semi-hibernation and at the end of the season when they have just hatched out (August to November). Don’t treat in the depths of winter if the soil is below 5°C, and don’t treat at the height of summer when it is too hot and dry for the nematodes to be effective. For the adults use the traps between June and September when they are around in large numbers.

The nematodes arrive in a sealed pack and should be used fresh. You can keep them in the fridge if you can't use them straight away, but they must be used by their use by date.  On the day of application remove them from the fridge and allow them to warm up to room temperature.

Follow the instructions carefully and don't save any part of the pack content or solution. 

Apply when the soil temperatures are above 5°C at least 3 hours of the day and keep the soil reasonably damp while the nematodes establish themselves. Vine weevil larvae should be treated from the spring when they first become active and then every 6 weeks throughout the growing season.  A treatment in the autumn just before the soil temperature drops will stop the grubs from overwintering in your garden. The nematodes do not kill the adults.  All our nematodes are pet and child friendly and will not harm plants.