Are tent caterpillars taking over your trees? Are they wiping out leaves? You can take steps to eliminate these creatures and prevent further damage to your trees. For instance, Safer® Brand Garden Dust is an OMRI Listed® treatment that kills over 20 varieties of caterpillars and worms – just what you need to rescue your trees!
So... What's a Tent Caterpillar?
Adult tent caterpillars aren’t caterpillars at all, they’re moths. These moths are usually tan or brownish in color with a wingspan reaching up to 1 ½ inches.
The larvae – the caterpillars – are black with rows of white dots or stripes the length of its body. Short hairs cover their body, which can be up to 2 1/2 inches long.
The eggs are laid as a group in a tube-like wrapping that encircles a tree branch or twig. These masses can contain up to 350 eggs and hatch in the spring. If you spot one of these egg masses, which makes a section of the branch look shiny and engorged, cut the branch below that point and dispose of the egg mass in the trash.
What's NOT a Tent Caterpillar?
There are many similar caterpillar/moth species that look a lot like tent caterpillars:
- Armyworms – These destructive pests target crops and lawns rather than trees. They grow up to 2 inches long and are hairless.
- Bagworms – These worms don’t look like a tent caterpillar, instead they are pudgy and hairless. Their nests, however, may make you assume they’re tent caterpillars. Bagworm nests are made of webbing, but appear messy and filled with pieces of plant debris.
- Gypsy Moths – These caterpillars have a yellow heads and a hairy body. Five pairs of blue dots, followed by six pairs of red dots, run along the length of their body. It’s easy to confuse Gypsy Moth Caterpillars and Tent Caterpillars. Luckily, both can be treated with the same Safer® Brand products.
Also be aware that there are multiple species of tent caterpillar. In the U.S. and Canada, others include western, forest and southwestern tent caterpillars. Forest tent caterpillars, by the way, don’t actually use tents – instead they congregate in social clumps on the trunk of a favorite tree.
Reproduction Patterns of Tent Caterpillars
Female moths deposit their eggs in the middle of summer. The eggs overwinter in a protective case that’s attached to an the branch or twig. The eggs hatch in the beginning of spring.
Emerging caterpillars spin a protective silk tent in the crotch of a tree. They feed on nearby leaves in the daytime, returning to their nest when finished. They will continue in this manner for the next month or two until they are ready to pupate.
During the next phase of its life cycle, the tent caterpillar will leave the nest and find an appropriate trunk or plant debris on which to spin its own cocoon. After 10 days to two weeks, the adults emerge as moths and the cycle continues. The tent caterpillar has one generation per year.
You can prevent tent caterpillar damage by eliminating the insects with a product such as Safer® Brand Garden Dust.
Tent Caterpillar Habitat
Found throughout the United States and Canada, these caterpillars prefer trees and shrubs of the hardwood deciduous variety, and cherry trees appear to be their favorites. Look for tent caterpillars in these trees and bushes:
- Oak Ash
- Sugar maple
- Wild Cherry
Widely recognized by their webbed (silk) tent structures, these larval insects can cause mass defoliation in a short period of time. Damage is relegated to the tree or bush where their tent is located. The species spreads to new trees when mature moths venture out to lay eggs.
Symptoms of Tent Caterpillar Damage
Leaves within three feet of a tent worm nest will disappear first. In other instances, an entire leaf cluster may be consumed. Additionally some trees may lose so many leaves that it appears to have dropped them in preparation for the autumn.
The most important symptom, though, is that you’ll see the tent caterpillars’ web structures. These nests are easy to spot, even when foliage is at its height in the early summer. As the caterpillars consume more and more nearby leaves, the tents will be even more evident.
Why do tent caterpillars create their silk tents? Caterpillars use them for shelter, and they enter them at night and during rainstorms. They tents may trap heat, too, allowing them to survive in the early spring and during chilly nights. The thick mass of silk also protects them from birds and other predators.
The web nests may also survive through the winter. Those that do will look ragged and dull compared to new creations.
When it’s time to spin cocoons, dozens of tent caterpillars will descend from their food source to the ground below. From there, you may spot them crossing roads and sidewalks as they search for the perfect spot to prepare for their transformation into moths.
Results of a Tent Caterpillar Infestation
Trees are often defoliated by tent caterpillars, especially if the infestation is a large one. These attacks are rarely fatal to the plant, though. It’s only after repeated attacks across multiple years that a weakened tree perishes, usually because it doesn’t have the strength to fight off another pest or an opportunistic disease.
Tent caterpillar infestations may also trigger a second, stunted rebud of leaves in the same season. The stress of the caterpillar attack and following rebud often stunts the tree’s growth for the next few years. However, if caterpillars are successfully treated, the tree should grow normally again.
Natural & Organic Controls
Safer® Brand offers a variety of options to control an infestation of tent caterpillars. These options are all OMRI Listed®, meaning they are compliant for use in organic gardening.
Safer® Brand Garden Dust and Safer® Brand Caterpillar Killer II With B.T. Concentrate are OMRI Listed® products that can be used to help control tent caterpillars. Each uses B.t. (Bacillus thuringiensis), a biological control that the caterpillars accidentally consume while attempting to feed normally.
Safer® Brand End ALL® is another option for fighting tent caterpillars.
When ingested, B.t. kills tent caterpillars, preventing further damage to your trees. The caterpillar eats the B.t. which is spread in powder form on leaves. Once ingested, it works as a gut rot poison that makes the caterpillar stop feeding. Once the caterpillar stops feeding, it dies within days, succumbing to malnutrition.
B.t. can be used on more than 20 caterpillar and worm species, but it has no effect on birds, earthworms or beneficial insects.
For even more options, explore the tent caterpillar control product page for details on Safer® Brand End ALL®. You can learn how each of these solutions target caterpillars and how they should be applied. Remember to carefully read and follow all directions on the product's label.
Safer® Brand’s B.t. products are very specific in how they target caterpillars and leaf feeding worms. B.t. will not harm children, pets or wildlife. It is recommended with any pesticide to test plants for sensitivity to the product. Spray a small section of the plant in an inconspicuous area and wait 24 hours before applying across the entire plant.
B.t. products should be applied when it is cooler, preferably later in the afternoon or early in the evening since the product breaks down in sunlight and heat. Carefully read and follow all directions on the product's label.
When applying a product with pyrethrins, which is used in Safer® Brand End ALL®, to infested plants, carefully read and follow all directions on the product labeling for application instructions. Do not spray End ALL® on plants in the peak of the day or when temperatures exceed 90°F.