Webworms (??) destroying Garden Sage plants

[saluqi]

For a number of years now I have grown one or another variety of Garden Sage in the ground, or in large pots. It has always grown vigorously and without much trouble. This year I started two pots, which until a week or so ago grew vigorously and seemed quite healthy. Now they are almost entirely defoliated, and covered mostly from underneath by silken webs. The leaves are eaten full of holes from underneath, until they are completely destroyed. I can provide photographs if that would help. When you turn over a leaf you find numerous slender, half-inch-long caterpillars that move quickly out of view. The plants are now - barely a week after the first obvious small round holes appeared in the leaves - almost completely destroyed.

I haven't seen this before, at least not on anything like the present scale. We are having extremely hot and dry weather - daytime temperatures up to and beyond 110 F., and relative humidity as low as 0% (really). Combine that with strong winds and it's hard to keep container plants alive - if not watered copiously in the early morning they would be wilted to the point of collapse by noon. Apart from the sage plants I have several kinds of hot peppers, and four tarragon plants I bought this Spring to replace ones I had had for several years but lost this last winter. Everything else is (given sufficient water) thriving, but the sage plants are an utter disaster. Before dousing the plants with insecticide (I generally prefer not even to have such things in my house) I am curious to know what beast this is, and also perhaps how to deal with it. I'd like to salvage the plants if possible, since it's effectively impossible to obtain replacements here until cooler weather arrives in October or November.

For pepper enthusiasts - I have Thai culinary, pequin, Caribbean red, and one Bhut Jolokia plant. And yes, I use them in cooking, that's indeed why I have them.

[imafan26]

For caterpillars I try Bt first. It works on most caterpillars. The other thing to do is put out a bird feeder to attract caterpillar eating birds. Don't feed them regularly, otherwise you will just be trading one problem for another.

Bt is sold as dipel or thurgicide. It is a natural bacteria that will pretty much infest the caterpillars and make them sick.

I don't have a large caterpillar problem since I have a lot of anoles that will eat them and most other insects hanging around the plants. I also plant nectar plants like fennel, marigolds, sunflowers, cosmos, alyssum, and cuphea to attract beneficial insects including parasitic wasps which will lay eggs on the caterpillars and destroy them from the inside out.

I have more caterpillars this year because I have a butterfly bush that insists on blooming and I have to keep cutting the flowers off and sometimes I am getting there a bit late. I need to move it to where it will do no harm.

[saluqi]

Bt = Bacillus thuringensis, I'm familiar with it though I never had to use it before. I'll have to look around. It's a three hour drive to/from anything resembling a garden centre around here. Not practical for me because of work schedule. FWIW this is mega-farming country and we are inundated in pesticides of all sorts, whether we will or no. They are sprayed from airplanes. Here I am surrounded by hundreds of acres of alfalfa, which attract a yellow butterfly (I think it's Colias eurytheme) which in turn attracts pesticide-spraying aircraft. None of that seems to have helped my sage plants.

Unfortunately my yard is inhabited by 10 Salukis, who pretty effectively discourage birds from landing (though I do have a flock of sparrows (we call them "English" sparrows in the U.S. <G>) who manage to eat most of my figs before I can pick them. The herb pots are outside the fenced yard (otherwise the dogs would uproot everything within a few minutes) but I also have a very territorial resident Mockingbird who doesn't tolerate anything else on his turf. Would Hummingbirds perhaps eat those caterpillars? We have lots of them here (mostly Black-chinned in summer, several others in spring and fall) and I could do (and in the past have done) more to attract them than I have this year. Is that the problem? Mea culpa?

We have a lot of Western Kingbirds (one of the Tyrant Flycatchers, for those who don't know them) and they breed in my trees, but they are mostly interested in flying insects and I can't imagine them creeping around my herb pots to pick caterpillars from under the leaves (and from under a thick layer of silk webbing).

If I knew which parasitoid wasp attacked those caterpillars I'd try to obtain a batch of them. I suppose a starting point would be to know what they are (the caterpillars, I mean)?

In the meantime I'm ready to spray with pyrethrum, pyrethrins, maybe even pyrethroids - I don't think those plants are going to survive more than a few more days, unless all the caterpillars suddenly drop off and pupate . . .

[applestar]

One thing you could do is use an old toothbrush (soft bristles would be better - do you use soft?) and try to brush off the web and caterpillars into soapy water. The soapy water is just to kill them and not to put on the plant so it can be anything including dish detergent. But if you think some would get on the plant (e.g. Need to rinse the toothbrush off in the soapy water), use real soap (I like Dr. Bronner peppermint liquid soap) or maybe veg wash -- something that doesn't burn the leaves and will not taste awfully awful.

It helps to put something (paper, plastic) down on the ground under the plant to so any that escape will land on it and can be easily captured.