Tent Caterpillar: “They’re baaaaack”!

Tent Caterpillar

“They’re baaaaack”! 

Have you noticed the tent caterpillars yet?

I saw the familiar web nest in my purple leaf plum, and weeping cherry tree today as I looked out my bedroom window to check the weather. Likely, most people never notice the tent caterpillars themselves, but the bags are hard to miss.

Tent caterpillars, commonly known as bag worms, spin their silk into a web nest (or “bag” or “tent) in the branches of trees where the limbs grow in two separate directions. This forked location provides a good strong foundation on which their nest can support the ever increasing weight of the local colony.

These nests house hundreds of larvae, protecting them from predators.

The larvae are not restricted to the nest, however. They spend much of their time eating the tree’s leaves, only returning to the safety of the nest when not feeding. During their early development, the larvae feed during the day and return to the nest at night. Later in their development, the larvae reverse this, feeding at night and retreating to the nest during the day. Tent caterpillars will spin a constantly growing “tent” in order to accommodate their ever increasing size. This tent will become more and more apparent as spring turns to summer.

Are tent caterpillars a problem? 

They can be. They voraciously feed on leaves and can defoliate large sections of tree quickly. The bag nests are also an eyesore. Tent Caterpillars are very active pests with ferocious appetites and will eat most any plant they find making a mess along the way.

How do I treat tent caterpillars?

Fortunately, there are some very effective treatment options for controlling tent caterpillars. It will be easiest and most efficient when done early in the season (now!). Also, treatment is best done at dusk, when you will have the best chance of finding the larvae in the nest. Break open the nest with a stick, and then spray with Borer, Bagworm, Leaf miner & Tent Caterpillar Spray, a natural, organic, bacterial insecticide, which is non toxic to humans, pets and beneficial insects.


1. Prepare the spray and be sure the sprayer you have will reach high enough to soak the nest.
2. Using a stick or pole, poke 3-4 holes into the tent. Holes should be large enough to allow for treatment to penetrate but not too large that all caterpillars fall out.
3. Once access holes are made, spray the solution you have already prepared onto the nest for a quick kill. Soak it to the point of runoff thus insuring the ones present will be killed and that there will be a lasting residual to get any that may be away.

Now that’s ‘advice you can grow with’!