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Birds and Wildlife

Western Tent Caterpillar
(and a Mole tip)

Polly Adcock
May 2021

While trying to stay CLEAN before leaving for an appointment, I spied a web on an evergreen shrub. This was the first week of MARCH 2020! Fearing I would forget about it, I went to investigate and sure enough it was THEM ---- Western Tent Caterpillars with orange and black markings. My Tennessee Mama called them bag worms (Perhaps Northwesterners are inclined to think more about camping.) Usually I would have clipped it off and burned it in the fire-pit but wanting to remain CLEAN, I clipped it and tied it in a plastic bag and tossed it in the garbage; hoping they wouldn't CHEW their way out!

These messy menaces come from a reddish-brown moth which lays eggs in late summer. The eggs winter on a branch in a ½ inch case which looks like a bubbly gray crust. By mid-April they wake-up. (Some must be early risers.)

They will attack deciduous trees—fruit, poplar, willow and wild rose. A few years ago it was a depressing sight on Hwy. 305 but WSU said if they aren't bothering garden, orchard plants, or close to house or deck, leave them alone. Even though they can defoliate trees, by thinning the canopy, it allows young conifers to stretch toward the sun. Caterpillar droppings help fertilize the understory.

Spraying pesticide works ONLY on the caterpillars. The web is waterproof and impermeable to toxins. Instead, spray leaves they eat with Bt (Bacillus thuringiensis). They will stop eating and die. Peeling the egg case from the tree branch in winter will curb population. If the caterpillars have white dots on them, they have been marked by a parasitic fly---just wait it out.

Don't prune the branches to get rid of them as that would disfigure the tree and deplete plant resources as much as the menace would do.

There are a forest tent caterpillars which are bluish with a black and white keyhole pattern. It is found throughout North America BUT its larvae does not make a web but instead weaves a silky sheet where they lie together during molting. These caterpillars prefer Aspen and Maple and will feed on most types of fruit trees.

One GOOD thing I found was they cyclical, happening about every nine years and lasting about three years while having only ONE generation per year. YES!

The Mole Tip

All last summer my neighbor and I dealt with Mole' the underground excavator who kept making skylights (brown mounds) in his/her tunnel. Nothing worked getting rid of it/them. While pruning rose bushes in February, I had a MEMORY blast. Twenty years ago I put rose stalks in the holes and it worked. (Supposedly moles are free bleeders. I cannot confirm that rumor but rose thorns are brutal!)

I cut up a BUNCH of stalks and crammed them in every SKYLIGHT ! So far --- so good. If you try this, be sure to cram the stalks deep so you will not stub your toe.