Tent Worms

I have a lot of what I call wooly worms this year. They are black with yellow down their backs. What do they eat? I usually see them in the fall, not in the spring. Thank you. Jonesboro, AR (zone 7)

What you are seeing are tent worms. I too have seen a huge number of these in my garden this spring.

The caterpillars hatch in early spring about the time leaf buds break. They have a voracious appetite for tender, new foliage, especially on fruit trees and roses.

As summer progresses, you will see their webs in the crotches and on the branches of trees.

In time the worms will metamorphose into a tan moth, which will mate, lay eggs and next spring new tent worms will emerge.

Every now and again there will be an outbreak and large numbers of tent worms will appear. An infestation will quickly defoliate a tree, but this is not fatal, new leaves will emerge. However, repeated infestations can weaken the tree making it susceptible to disease and other pests. So it’s a good idea to try and minimize the population.

One method of control is to simply remove the webs from the tree with a long stick, dip the web in soapy water and then dispose of it.

The best time to remove the caterpillar tent is early morning or evening while they’re still likely to be in the nest. 

Creating a welcoming environment for birds is an excellent and natural way to cut down on the population.

Spraying with an insecticide is also effective. For the least impact, choose an organic product as Bacillus thuringiensis (Bt). This kills tent caterpillars while remaining safe to other wildlife.

To get to the worms it’s important to tear into the webbing and spray inside. This treatment may require several applications and anytime you are spraying you should always hold off if rain is in the forecast.