Last week I found vine weevils on the rim of my the pot my orange tree lives in. It stands next to my 'nursery' of seedlings, so potentially hundreds of plants could be affected.
Last week I found vine weevils on the rim of the pot my orange tree lives in. It stands next to my 'nursery' of seedlings, so potentially hundreds of plants could be affected. The adults cause little damage, save for a few nibbles on the edges of leaves. But their larvae can kill plants by eating their roots.
The adults will lay eggs anywhere, but prefer an open soil in which the larvae can move around freely. A light, peat-based compost is ideal for them. I don't use peat, so I consider this invasion to be extremely unfair.
So what to do? Pesticides applied every spring and autumn will kill the larvae. But I worry that the active ingredient (thiacloprid - a nicotinoid compound related to imidacloprid) also kills bees and other wildlife (you can read more on the subject here). The theory is that the thiacloprid is absorbed via the roots into the plant's sap, pollen and nectar, and that anything that feeds from it can die. Thiacloprid is active for up to three months and imidacloprid can last for up to six months.
I spoke to David Morris from Bayer, which makes Provado Vine Weevil Killer 2. He said there was no evidence to suggest that thiacloprid killed bees. But I choose not to use pesticides in my small garden, so have opted for alternatives.
In future, I'll empty out all my pots and inspect them for grubs each spring. But this time I'm using nematodes. These are harmless to wildlife, but attack and kill vine weevil larvae within three weeks. I've heard mixed reports about nematodes - some people claim they don't work - so I'll repot my orange tree next month to be on the safe side.
I've been leaving my girlfriend gardening tasks to do while I work: transplant the zinnia, sow more basil, repot the strawberries etc. She proudly showed me the little pots of zinnia one evening. "Did you find any little white grubs in the compost"? I frantically asked. "No". Phew! "But there was one in the strawberries. It was cute and wriggly. And an earwig".
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