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Vine weevil infestation

#1 · 6th April 2025, 10:45 am

I've discovered a massive infestation of vine weevil grubs in my garden. I created and planted up loads of new beds in my back garden last year. They have eaten the roots of most of my new garden (They are also in my front garden but not as many as its heavy clay soil). I've been digging up the grubs in their hundreds and have probably reached over 1000. The bigger ones i put on the bird feeder and smaller ones I put in the bin.

Yesterday I had two adult weevils in the house (the picture is from my bathroom). Not sure if they have hibernated in the house or were grubs feeding off my houseplants.

My question is do you think it's worth using nematodes? Would these also affect other insects in the garden and end up destroying a whole ecosystem?

I pretty much never use chemicals but i definitely can't use chemicals in the back because I have a Horsfield Tortoise that lives in the garden. (This also limits the plants I can use).

Thanks for any advise,

Beks

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#2 · 8th April 2025, 12:11 pm

Quote from Lee Garden Ninja on 8th April 2025, 12:11 pm
Hi @beksb
Thanks for your comment about Vine weevils. These pesky critters can cause all sorts of damage to gardens, greenhouses and plant rootstocks!
Once you have vine weevils, it can be really tricky to get rid of them. It sounds like you're being overrun with them, and the quick answer to the question 'do nematodes work on vine weevils?' is a resounding YES! Nematodes are the best environmentally friendly way to keep vine weevils under control.
Let's also take a closer look at what vine weevils are (I've written about Vine weevils attacking Magnolia trees too), how to stop them and what control measures other Garden Ninjas can benefit from.
What exactly are Vine Weevils?
Vine weevils (Otiorhynchus sulcatus) are the ultimate plant nightmare, quietly wreaking havoc behind the scenes in the soil by attacking plants roots. You might notice your once-thriving plants suddenly wilting and collapsing, and no amount of watering will bring them back. The culprit? Vine weevil grubs have gone to town on the roots, devouring them completely, stopping the one source of both water and plant food from being uptaken.
These pesky grubs are particularly fond of potted plants and containers, though they’ll attack plants in borders and beds too. The real problem lies beneath the surface, where the grubs feast out of sight, often until it’s too late.
Identifying Vine Weevils
Vine weevil eggs are laid in the roots of your plants. Making them the most tricky, hidden spots where it’s hard to spot the damage in time. The eggs hatch into small, 10mm ‘C’-shaped grubs with cream-colored bodies and brown heads. These silent destroyers gradually munch away at the root system, leaving the plant to slowly starve, wilt and die. First, the leaves turn yellow, then the plant wilts and collapses as the roots can no longer supply nutrients.
What do they look like?
Adult vine weevils are small, dusty grey or black beetles, about 1cm long, and they can’t fly. Interestingly, all adult vine weevils are female and capable of laying up to 1,000 eggs each season. These eggs hatch in spring, giving rise to the next generation of grubs. They reproduce at an insanely fast rate which is why they often catch gardeners out.
Damage and Symptoms
Adult vine weevils munch on the edges of leaves, leaving irregular notches. Meanwhile, the grubs feast on the plant’s roots, stunting growth and causing the plant to collapse when it can no longer get the nutrients it needs. This damage is most visible from autumn through to spring. It is often brought in by shop-bought plants, particularly heucheras and tiarella.
How to Control Vine Weevils
Dealing with Adult Vine Weevils:
The best way to tackle adult vine weevils is to catch them at night. Armed with a torch, shake the plant gently, holding a tray or newspaper underneath to catch the beetles as they fall. Pick them up, squish them, and dispose of them. You can also use a specially formulated chemical control for ornamental plants in pots and containers. Whilst spraying with a systemic and contact insecticide at dusk works I'd always advocate against chemical sprays as you can read how destructive they are here.
Dealing with Vine Weevil Grubs:
Introduce nematodes—tiny parasitic worms like Steinernema kraussei—to fight back. These beneficial bugs won’t harm your plants but will target and kill the vine weevil grubs. To make the most of them, water them into moist soil at temperatures above 5°C during late summer before the grubs get too big. For potted plants, nematodes work best as does removing the soil and potting on infested specimens.
Preventing Vine Weevils
Before moving any container plants into a greenhouse or conservatory, inspect the compost thoroughly for white grubs. If you find any, dispose of the compost, rinse the pot, and clean the plant’s roots before replanting. You can also attract natural predators like birds, frogs, and hedgehogs to your garden to help manage the vine weevil population. A wildlife pond is the best solution for all of these benefitical garden creatures!
https://youtu.be/iztGt30W7SE
Another clever prevention method is to create a barrier around your pots. Wrap parcel tape around the base, coating it with non-drying insect glue. Since vine weevils can’t fly, this will trap adult females before they can lay their eggs. Timing is key: do this from August to September outdoors, or year-round in a greenhouse.
Lastly, make it a habit to inspect your plants regularly. Early detection is the best way to prevent a serious infestation.
Vine weevils love plants like:
Begonias
Bergenias
Fuchsias
Heuchera
Primulas
Strawberries
Succulents, and more.
Take a moment to lift plants from their pots and check the rootball for signs of damage or infestation.
Do let us know how you get on!
Lee Garden Ninja

Hi @beksb

Thanks for your comment about Vine weevils. These pesky critters can cause all sorts of damage to gardens, greenhouses and plant rootstocks!

Once you have vine weevils, it can be really tricky to get rid of them. It sounds like you're being overrun with them, and the quick answer to the question 'do nematodes work on vine weevils?' is a resounding YES! Nematodes are the best environmentally friendly way to keep vine weevils under control.

Let's also take a closer look at what vine weevils are (I've written about Vine weevils attacking Magnolia trees too), how to stop them and what control measures other Garden Ninjas can benefit from.

What exactly are Vine Weevils?

Vine weevils (Otiorhynchus sulcatus) are the ultimate plant nightmare, quietly wreaking havoc behind the scenes in the soil by attacking plants roots. You might notice your once-thriving plants suddenly wilting and collapsing, and no amount of watering will bring them back. The culprit? Vine weevil grubs have gone to town on the roots, devouring them completely, stopping the one source of both water and plant food from being uptaken.

These pesky grubs are particularly fond of potted plants and containers, though they’ll attack plants in borders and beds too. The real problem lies beneath the surface, where the grubs feast out of sight, often until it’s too late.

Identifying Vine Weevils

Vine weevil eggs are laid in the roots of your plants. Making them the most tricky, hidden spots where it’s hard to spot the damage in time. The eggs hatch into small, 10mm ‘C’-shaped grubs with cream-colored bodies and brown heads. These silent destroyers gradually munch away at the root system, leaving the plant to slowly starve, wilt and die. First, the leaves turn yellow, then the plant wilts and collapses as the roots can no longer supply nutrients.

What do they look like?
Adult vine weevils are small, dusty grey or black beetles, about 1cm long, and they can’t fly. Interestingly, all adult vine weevils are female and capable of laying up to 1,000 eggs each season. These eggs hatch in spring, giving rise to the next generation of grubs. They reproduce at an insanely fast rate which is why they often catch gardeners out.

Damage and Symptoms

Adult vine weevils munch on the edges of leaves, leaving irregular notches. Meanwhile, the grubs feast on the plant’s roots, stunting growth and causing the plant to collapse when it can no longer get the nutrients it needs. This damage is most visible from autumn through to spring. It is often brought in by shop-bought plants, particularly heucheras and tiarella.

How to Control Vine Weevils

Dealing with Adult Vine Weevils:
The best way to tackle adult vine weevils is to catch them at night. Armed with a torch, shake the plant gently, holding a tray or newspaper underneath to catch the beetles as they fall. Pick them up, squish them, and dispose of them. You can also use a specially formulated chemical control for ornamental plants in pots and containers. Whilst spraying with a systemic and contact insecticide at dusk works I'd always advocate against chemical sprays as you can read how destructive they are here.

Dealing with Vine Weevil Grubs:
Introduce nematodes—tiny parasitic worms like Steinernema kraussei—to fight back. These beneficial bugs won’t harm your plants but will target and kill the vine weevil grubs. To make the most of them, water them into moist soil at temperatures above 5°C during late summer before the grubs get too big. For potted plants, nematodes work best as does removing the soil and potting on infested specimens.

Preventing Vine Weevils

Before moving any container plants into a greenhouse or conservatory, inspect the compost thoroughly for white grubs. If you find any, dispose of the compost, rinse the pot, and clean the plant’s roots before replanting. You can also attract natural predators like birds, frogs, and hedgehogs to your garden to help manage the vine weevil population. A wildlife pond is the best solution for all of these benefitical garden creatures!

Another clever prevention method is to create a barrier around your pots. Wrap parcel tape around the base, coating it with non-drying insect glue. Since vine weevils can’t fly, this will trap adult females before they can lay their eggs. Timing is key: do this from August to September outdoors, or year-round in a greenhouse.

Lastly, make it a habit to inspect your plants regularly. Early detection is the best way to prevent a serious infestation.

Vine weevils love plants like:

Begonias
Bergenias
Fuchsias
Heuchera
Primulas
Strawberries
Succulents, and more.

Take a moment to lift plants from their pots and check the rootball for signs of damage or infestation.

Do let us know how you get on!

Lee Garden Ninja

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