The Fascinating World of Bagworms: An In-Depth Look at Their Lifecycle and Behavior

Date May 10, 2023

Author TreeNewal Staff

When you walk around your property, do you notice what appears to be clumps of brown leaves attached to your trees? If so, you might be dealing with bagworms. These insects spend their entire lives in a protective “bag” constructed out of silk, and they move along and feed on foliage until the end of summer. Read on for an in-depth look at the fascinating world of bagworms involving their lifecycle and behavior.

What Are Bagworms?

Image via Flickr by jinkemoole

Bagworm moths are perennial insects that tend to live in evergreens and junipers and cause extensive damage to trees and plants. Adult males are dark and hairy and have a wingspan of about 1 inch. Adult females remain caterpillars, resemble maggots, and are yellow. They’re often thought to be poisonous because they can kill plants, but they’re not.

When the summer ends, bagworm caterpillars stop feeding and fill each bag shut, securing them to a twig or stem. The caterpillar then transforms into a moth. However, the adult female remains inside the bag and awaits a winged male moth to find her. After mating, the female produces approximately 500 to 1,000 eggs before dying. These eggs remain in the bags until the following spring and hatch around mid-June to begin the cycle again.

What Do Bagworms Eat?

Bagworms tend to feast on the leaves of numerous types of plants. They typically live in the plants and feed on them. Bagworm larvae are parasitic, feeding on leaves and evergreen needles. When the larvae eat the leaves, they leave tiny holes in the foliage. According to Iowa State University, bagworms can eat the foliage of 128 different trees. The more popular ones they feed on include the following:

  • Bald cypress.
  • Black locust.
  • Boxelder.
  • Maple.
  • Oak.
  • Pine.
  • Rose plants.
  • Spruce.
  • Sycamore.
  • Willow

How Do You Control Bagworms?

Bagworm moths can cause extensive damage to plants, although deciduous plants can withstand the onslaught of these insects. Deciduous plants can deal with these moths because they produce new leaves annually. All other types of plants cannot survive bagworm attacks.

You can control bagworms either naturally or chemically. Naturally controlling them involves manually removing their nests, which you might find hanging from trees in the fall or winter. Remove these bags anytime before June since the eggs will begin to hatch after then. Chemical removal involves spraying the young larvae with an insecticide from late June to early July. These insecticides become less effective as the season progresses due to the larvae increasing in size.

If you need assistance in dealing with bagworms, reach out to the professionals at TreeNewal. We have numerous ISA-certified arborists on staff who can offer pest control services. They know how to treat and prevent bagworms from infesting your trees and shrubs. In addition, our staff members are trained to properly and safely dispose of infected trees, branches, and other foliage. Contact us today to set up an appointment, and we’ll send a certified tree arborist out to inspect your trees.