I have handpicked weevils under a Hemlock til I am cross eyed. They are so numerous in my yard that I picked over three hundred (yes I counted) one night, stomped them to thier maker, went in to sit for a bit. Came back out and lo and behold... many many more had arrived!! I hunt them at night with a flashlight and a beer mug to drop them into. How do I reduce thier numbers other than handpicking? I am an organic gardener. I would like to stay away from pesticides if possible. The Hemlock has a sitting area nearby, and small kids play around it as well. Thanks
Hello, I wonder if you asking about black vine weevil. It is important to identify the pest before treatment is given. For example, if you were using nematodes as a biological control method, you would want to introduce them when the weevils are in their larval stage. This varies from insect to insect, and may not be effective at all if the pest is not identified properly. If black vine weevil is your pest, the link provides suggests some organic methods of control, specifically the "habitat modification" and "biological control using parasitic nematodes". Raakel
Yes. One of the types is a Black Vine Weevil. The most prevelant tho', is brown in colour and a bit smaller in size.
I'm having a bad year for weevils too, except that I seem to be finding incredible numbers of larvae, not much adult damage yet. At least I think they're weevil larvae, some are smaller than I"m used to finding. It is daunting. I've never used nematodes but I think I'm on the verge of trying them. The only comfort I can offer is to say that if you can persist, the reward comes the following year in that you won't have to be doing much of this at all. Also, you might be better off using the 'quantity' method if you have that many: lay a newspaper or sheet down under the plant, shake the plant, collect the bounty, and stomp as usual. Reapply an hour later if necessary!
Also, another poster reminded me a couple of days ago about the "fake cover" method; leave a piece of wood or piece of newspaper under the plant during the day and they'll go there for shelter. You can pick it up during the day and "harvest" them.
My experience with the nematodes has been excellent. Our young clematis armandii and embothrium plants were being shredded by weevils in spring/05, picking adults was always helpful but left considerable damage (not good esp. when you're expecting to sell the plants). We applied the nematodes from Koppert last fall, I think it was October, which was a bit later than the suggested Labor Day optimum timing, but this spring we have seen almost no damage. The established rhodos in the garden were also treated, and have been much happier looking and undamaged for the first time in memory...I'm sure their roots are far better without the grazing of those weevil larvae. I am hoping for some long term protection, tho the suppliers aren't encouraging about it...just dreaming that some of those nematodes have found enough to eat to keep a population in my soil, so we might not need to reapply every year (?). Even so, it was $20 well spent for my situation.
Are nematodes safe for use on berry plants (when the berries are greedily eaten all summer long)? I've got a serious black vine weevil infestation among my raspberry bushes (for the 2nd year in a row!) and I'd prefer to avoid picking off each bug by hand (& then what do I do with them??), so I'm looking into other alternatives. I don't know if SOME of the weevils are still in their larval stage, but I've definitely picked off some pretty big ones in the last couple days, so I need a solution that's going to work on adults as well. The 'fake cover' method sounds like a great idea, but probably pretty slow... especially since I know that my voluminous blackberries will likely get re-infested this year too. They also seem to be nibbling at my salmonberries too, so the problem is only getting worse. Any suggestions for large-scale removal that'll be safe for humans & pets, but also effective on adults? Thanks so much! note: black vine weevils were certainly the *most* common species on my plants last year, but I'm not 100% sure that they're the only ones I saw... there might have been brown ones too.
Fern--the nematodes are applied to the soil, so they won't really be affecting the berries you eat anyway (tho they shouldn't be bad along with all the other microbes on the berries we eat without washing!). Also these are effective only on the larvae, so application in about Sept. is recommended when the eggs have all hatched and the vulnerable larva phase is at it's peak. Some beetles will overwinter, I don't think they will be controlled by the nematodes as only larvae ingest the nematodes in the soil...making yearly applications a likely possibility. My experience was that the adult beetles have to be hand picked for the time being to avoid the worst of the damage, until the nematodes can take out the next generation and break that cycle. Sounds like you have an infestation like I had, just shredded the young leaves on the most precious plants!
Fern: once picked, you crunch them underfoot. Brutish, but effective. One thing I learned last year that was a bit of a revelation... I thought I had a disastrous invasion of weevils as there were huge and copious cutouts of the leaves of several of my plants. These cutouts were half-circles, however, and not U-shaped, so I asked on a forum what this might be. The answer was leaf-cutter bees, a harmless local resident. They are back this year too; makes the plants look funny but doesn't kill them. If you're actually seeing weevils of course this isn't relevant, but if you're just reacting to your plants looking shredded... check the shape of the cutouts.
Wow. Thanks guys! I guess I'll wait until Sept before buying nematodes, and just crunch (or relocate?) until then.. And unfortunately, KarenL, I have seen the weevils 'in person' not just their work, so I know that they are the ones doing the damage. :( By the way, I've noticed that some of the berries themselves are being damaged too.. The berry's basic structure is still a-ok, as is about 60-90% of the red juicy flesh. But then in other spots, the fleshy bits have been eaten (?) away in places, leaving only the brown seed underneath. Is that the weevils again or do my raspberries have another foe? Anyway, thanks guys. Good info!
I used to succumb to empathy and relocate the little pests too, but I have read some interesting commentary over the years about how far they can travel, and that they will travel to their preferred plants. Also, they will do damage to plants whereever you put them, and no plant needs that kind of attack, and will only build up a new population "over there" from which they can re-infest your yard and others' even if you do succeed in banishing them from your property. They are in an introduced pest with no local natural control, and don't die out in our winters, so unless we destroy them they will destroy our vegatation. Too much empathy can be self-defeating, and this is such a case!
Sigh. Ok.... (ps: the false covers I put out have only attracted wood bugs & slugs so far, not weevils - arg)
If you do decide to use nematodes, I would suggest you check on availability now and put your order in. Local supply is limited. I will be putting out nematodes (Steinernema) for cranberry girdler in another two weeks but ordered them in early May to ensure I could get enough. The rate should be about 70 million per 1000 sq.ft. for problem areas and 35 to 50 million for maintenance. They are easy to apply either through an irrigation system or with a backpack sprayer. Apply them in the early evening to already moist soil then water them in. Keep the soil moist for two weeks following application.
