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Eastern tent caterpillars: Are they as awful as they look? Garden Q&A

My neighbor said to burn these webs out of the crotches of my wild cherry tree. With what? A flame thrower? What do you suggest?

Oh, my — a big ‘No” to that. That cure could be much worse for the tree than the “disease”, i.e. Eastern tent caterpillars. We think of their webs as unsightly because we are taught to think that way, but these short-lived caterpillars have minimal overall impact. Eastern tent caterpillars are native and have coexisted with native trees for millennia. They are easy food for over 60 bird species, including orioles, as well as frogs, mice, bats, reptiles, squirrels, skunks — even bears.

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Webs in the crotch of a wild cherry tree.
Webs in the crotch of a wild cherry tree. (Ellen Nibali)

Mature trees tolerate the caterpillar feeding and, even when a tree is completely defoliated, it re-leafs, resulting in little negative effect. On small or young trees, however, pull out the nest with gloved hands or break it up with a long-handled tool. It can be sprayed, but only is effective when caterpillars are small. Eastern tent caterpillars have a single generation a year and finish feeding by the end of May. Then they spin cocoons, turn into small brown moths (that birds also eat), mate and lay eggs in a 1-inch mass stuck on a twig like a black styrofoam capsule. Populations vary greatly from spring to spring.

Incidentally, the tree webs you see in autumn, at the ends of branches, are fall webworms, whose treatment is the same.

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Last fall when I went to pull a carrot, the whole carrot was missing! The top was green and normal. I’m sure something tunneled under and ate every single carrot! How can I discourage that? There may have been tunnels in the garden but not obvious ones. My husband mowed a large field nearby and reported lots of mice, voles and moles evacuating the area.

Obvious tunneling with cracked raised earth aboveground is the work of moles, but moles do not eat roots, nor do mice. The only critter that would consume the entire root of a carrot and not the top is a vole. With a “v.” Voles looks like a mouse with a short tail and are destructive. They eat bulbs and roots and gnaw the base of trees and shrubs, often killing them. Vole tunnels can be aboveground (especially under snow or in high grass) or not visible at all except for the half dollar-sized entrance to their slanting tunnel. They kick out no soil. You can put mouse snap traps baited with apple at the tunnel entrance to catch voles.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Maryland’s Gardening Experts” to send questions and photos.

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