They're Tent Caterpillars!

"Is this the Jim Anderson who writes for The Nugget?" the caller asked.

"Yes, it is," I replied. "What can I do for you?"

"I want to know what those ugly, twitching, hairy things that are all over my bushes!"

And that's the way it's been at least once a day over the past couple of weeks: phone calls and, "Oh, by the way, Jim..." stops in the post office, library, gas station and grocery store.

Those are western tent caterpillars (which will eventually become moths) chomping the leaves of antelope bitterbrush. In Central Oregon, you sort of grow up with tent caterpillars. We notice them out of the corner of our eye as a causal part of the landscape, but this year, they seem to be more than casual.

As to whether tent caterpillars do any harm, that depends on your perspective. They can almost defoliate their host plant, which, from the human perspective may be "harmful." From the perspective of nature, however, what's going on is between moths, plants, parasites, predators, a whole lot of biology, and chemical and energy exchanges, plus other things I can not contemplate. So the question about "harm" is relative to the human perspective, not nature's.

The life history of tent caterpillars is fascinating. The eggs hatch as soon as the cold, frosty nights are gone in spring. (Ha! "Spring" in Central Oregon means almost nothing regarding air temperature. Over the millennia I think tent caterpillars - like so many other organisms in our neck of the woods, including you and I - have adapted to the extreme changes we experience in our so-called "spring.")

Be that as it may, tent caterpillars MUST get a head start on spring, and emerge at the same time the new buds pop open. They're in a race with their host plant; they have to eat the young tender leaves before they're too tough to chew on. If you watch caterpillars over their short lifetime, you'll see they grow very rapidly, almost at the same rate as their food plants.

The twitching business is group protection strategy to being disturbed. A bird that may be able to eat that "hairy" body will be confused by all the movement and perhaps fly away without snapping up even one - or conversely, some other bird may grab the one nearest it, but then find it can't keep it in its mouth because of the irritation from the chemicals in the spike-like "hairs."

Their group protection works, and on cold nights they'll get under the silken tent and huddle together to keep warm. Like the honey bees that maintain their home at 90 degrees winter and summer, tent caterpillars elevate the temperature within their huddled masses over 50 degrees warmer than the surrounding temperature on cold, sunny mornings.

For control, some people cut out the caterpillars and their tents on cold mornings and burn them (in a metal bucket away from buildings and anything else that can catch fire). If you feel it's necessary to remove them from the bitterbrush, this is the best form of "control."

Please stay away from chemicals. There are a host of parasites and predators that depend on tent caterpillars to make a living ("natural control" if you will), plus, there are other things going on we don't understand. What we do understand is that chemicals are bad news for the good guys as well as the bad guys in your garden. Who knows, maybe all that frass (caterpillar poop) dropping into the soil beneath the bitterbrush is fertilizer and therefore "good" for the

plant.

As the "Bard of the North," Robert Service, says in his delightful work, "The World's All Right:

There's much that's mighty strange, no doubt;

But Nature knows what she's about;

And in a million years or so/ We'll know more than to-day we know."