PO Box 2458, Tijeras NM 87059

Mountain Gardens--finding success with plants for the high desert and East Mountains of New Mexico

Friday, August 12, 2011

Tent Caterpillar ?

If you see an ugly mess like this in your shrubs or trees, you can be sure you have caterpillars. The silky webbing is characteristic of tent caterpillars, webworms, and others--most of them moth larvae. The granular matter in the web is frass--caterpillar poop. Following a frass trail is a good way to spot culprits that are better hidden than these characters. Hornworms, the big, bright green caterpillars with the hook on their tail that are chomping your tomatoes to the ground blend perfectly--but they leave big plops here and there.

This is some kind of tent caterpillar (please correct me I'm wrong--I couldn't make a positive id). He (or she, maybe it?) and sibs have been wreaking havoc in the mahonias (Oregon grape holly) outside the gate at Mountain Gardens. Tomorrow I'll dust them with some Bt, (Bacillus thuringiensis) a bacterium that preys only on caterpillars. After eating some, any caterpillar will stop feeding within an hour or two, and die within a day or two. ANY caterpillar--that includes our beautiful butterflies, the champion pollinator hawkmoth and others, so I only resort to Bt after other methods of control have failed--washing off with strong blasts of water, hand picking, etc. We also use them only if the plant under attack  is likely to be completely defoliated (a little munching here and there is part of the cycle). Bt comes in a variety of forms. We use Dipel, a dust, or Thuricide which can be mixed with water and sprayed on your plants. There is a special Bt to use in water to control mosquito larvae. Bt is organic and safe to use--there have been thousands of studies--and it doesn't harm any of the beneficial critters in your garden, or your pets or kids. It's a naturally occurring soil bacterium.

Countdown to ArtFest on August 20/21--only a week to go!? Where has the season gone?

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