A butterfly emerging from a cocoon is a magical sight. Witnessing it spread its wings, the beautiful colors stretching out in the sun for the first time, it’s mesmerizing. But, somehow that sense of awe doesn’t translate when a black, fuzzy moth emerges from its bag. Those moths, likely bagworms, were busy eating your evergreen or tree before they made their debut. Bagworms can be a destructive force on your trees but are often overlooked by property owners. Allow us to familiarize you with these little destructive wonders and teach you a few things to help you bag those bagworms.
Bagworms are tiny and often go unnoticed. So, while you probably won’t see the bagworms themselves what you may see are their 2” homes hanging from the branches of your trees. These homes will sometimes be mistaken for cones on evergreens. In the fall, the insects use their silk and pieces of the tree to create a camouflaged, cocoon-looking bag, which they fill with up to 1,000 eggs. Yep, that’s a lot of baby bagworms.
The eggs hatch in late spring or early summer, when super tiny, black larvae emerge. At 2 mm, they’re barely larger than a pinhead, which makes them light as a feather. The caterpillars use their silk thread as a parachute to travel to nearby trees and begin building a new home (or bag) there. Pretty soon, your backyard has become a bagworm city.
The Damage They Do
Bagworms prefer juniper, arborvitae, spruce, pine, and cedar but also attack deciduous trees. On evergreens, they’ll eat lots of the buds and foliage, causing branch tips to turn brown and then die. If they eat more than 80 percent of the tree, the entire evergreen may perish.
On deciduous trees (those that lose their leaves in winter), bagworms chew small holes in the leaves and can cause defoliation. Generally, these trees will bounce back if you get rid of the bagworms. So how do you get rid of them? We are glad you asked.
Let’s Bag ‘Em
Fair warning, you are not going to like this. The best way to manage bagworms on small shrubs and trees is by handpicking or cutting the bags from infested plants. This must be done during fall, winter or early spring before the eggs hatch.
But if the bagworms are too numerous to handpick, an insecticide application can be used. The best time to apply an insecticide is from early to mid-June while the larvae are small. Otherwise, treatments will not be as successful. Feeding by mature caterpillars slows in August before pupation into adults, so chemical control in late summer and fall is not as effective.
Not sure if you got a bagworm problem? That’s why we’re here! Our certified arborists have the knowledgeable know-how to help your trees remain free of infestations and diseases or return them to their balanced state of health. If you have further questions regarding signs or symptoms of bagworm infestations, feel free to leave it to us. You can each us at 717-564-1995 to learn more.