Hi all, I posted earlier about invisible insects on my climbing hydrangea (Hydrangea anomala ssp. petiolaris), and was pointed in the direction of root weevils. I also have a schizopragma that is being devoured. Do these plants suffer from weevils as well? Thanks. Wendy
Heat and drought stress can leave under developed and deteriating tissue, which can also leave the impression of insect damage.
Thanks for the suggestion. (Sadly), I have only *full* shade in my garden & with all the moisture we have been getting in Vancouver, drought is not an option. The leaves near the base of the plant have almost been completely eaten. Those vines climbing seem to have fared better. Inseciticidal soap has had no effect. I've just doused it with Bug-b-gone http://www.scottscanada.ca/index.cfm/event/ProductGuide.product/documentId/7FD16E574F3AC7D79E9E2BFE87D0E6B1- I hope that will help.
Full shade won't really make a huge difference during severe heat and drought conditions. The summers of 02, 03, and the worse drought conditions of '04, may play a large roll in noticable tissue damage this year. From what you describe, does sound similar to weevil damage, although weevils do prefer softer new tissue. I don't know if Carbaryl as an insecticide is permitted for use in Vancouver. You could first try putting a few blocks of wood on the ground near the base of your vine and try to create a home for weevils underneath them. Check in the morning for weevils and just kill any you may find.
Thanks Jimweed. I've given it a blast with Bug-B-Gon, which contains carbaryl. I hope that helps out.
I have had weevils for years and usually am able to keep them under control by doing night hunts in spring; you can catch them eating then. Putting a board down to catch them during the day is also good, thanks for the reminder of that, Jimweed. Also, whenever I dig I am on the lookout for the creamy-white larvae, sometimes with legs already emerging, of which I have squished hundreds this year so far. They are bad this year. However last year I had some leaf damage that looked different from the usual u-shaped notches. These weren't notches, but bigger semi-circles. I found out these are cut-outs from leaf miner bees, and they are harmless. If you do use manual methods, make sure you are familiar with what weevils look like so you don't go killing beneficial bugs like ground beetles by mistake.
Karin, picking weevils by hand is probably the most effective control. They may be chewing on a plant on 1 side of your garden and live on the other, they do move around quickly when they want to. So soil drenching with insecticides is so hit and miss its generally not very effective. Being that they are such a large insect, systemic and contact insecticides are not always that effective either. Unless mixed at a high label rate, and most premixed ready to use products sold over the counter are not of high concentration. Most insects come and go anually and don't really do much damage, a few bites out of your leaves is only natural looking, and I spend all day talking people out of insecticide spraying. But weevils, adult and larvae both do damage and have long life cycles, so hunting them down is well worth the effort.