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I have the most horrendous vine weevil problem everything was eaten last year. I have tried nematodes and provado but with little effect. In desparation i dug up the worst ones and found the grubs , removed them the plant and soil, but to do this with my whole garden will cost a fortune. I find it totally demoralising, is there any plants they dont like ?. I have found on the underside of the plants as well,and found them mating on the plants too, and i have actually found them indoors which is really worrying as we dont have any plants indoors. Most of my plants were brought from garden centres where i think they are imported from abroad, could they have eggs in them?. Im not sure what to do next really the nematodes are applied twice yearly as per instructions and the same with the proado. What is the answer to this awful problem.
Wikipedia says imidacloprid is sold under different brand names one of them being Provado. This is NOT for use on edible crops.
All vine weevils are female. The adults are not the real problem. They disfigure leaves by biting chunks out of the edges. They don't fly, and walk about during the night, moving from plant to plant munching and laying eggs. You can only see them at night, and the best way is to lay newspaper under a plant they are attacking and shake it. they drop onto the paper. They lay eggs several times a year, and these hatch out at irregular intervals into the larvae that do so much damage.By the time you notice the symptoms of a larval attack it is often too late. Use Provado Vine Weevil Killer as a preventative, (not Provado Ultimate Bug Killer, which is different). Don't use it on edible crops like strawberries. You need to use it twice a year as the weevils can come back 8 weeks after application when it has worn off.
On edible crops you can use nematodes, but they only work from April to October when the soil temperature is above a certain temperature (can't remember but think it is around 5 C. The only alternative is to remove the plants in the dormant season, wash the roots thoroughly and replant in fresh compost. Remember that if you don't see larvae it does not mean there are not tiny eggs that will soon hatch into larvae.
Because it's expensive stuff, I only use Provado on pot plants, which are much more vulnerable, and on heucheras and sedums in the garden soil. If I am overwintering pots in the greenhouse I occasionally tip them gently out of the pot, check for grubs, and then put them back.
This is a vine weevil adult.
This is a larva (grub)
my garden centre warned that overuse of the insecticide will result in build up of tolerance in the bug, and kills all the other insects too. last autumn i used nematodes, ordered via the internet. they had to be applied in the evening, to damp soil, and the soil had to be kept damp for 10 days thereafter, so that the nematodes could move around in the soil. it was recommended to use the nematodes only in warm soil, in the spring and autumn. it seems to have helped, but then perhaps our weather has been too cold for the vine weavils to hatch yet. the garden centre advised that nematodes are not really effective unless under perfect conditions - warm, moist and friable soil.
Have a look at this site, very good pics and advice.http://apps.rhs.org.uk/advicesearch/profile.aspx?pid=234
The standard chemical treatment used to be Armillatox. However, since the manufacturers couldn't afford the high costs of testing etc. the product is now sold for cleaning greenhouses, paths etc. (A bit like Jeyes fluid, I suppose).
Where there is a large ornamental area to deal with, you can still used the product. www.armillatox.com will give the dilution rates.
I have used it successfully where my rhodos and azaleas were being munched. For pots I use Provado. I don't (fingers crossed) have a problem with edibles.