Bagworms, despite their name, belong to the moth family Tineoidea, not worms, and are recognized for the worm-like appearance of their larvae. These insects create protective cocoons by stringing together plant debris and silk, a behavior that spans their life cycle. They attack a wide variety of trees and pose a threat by inhibiting photosynthesis and weakening the trees, making them susceptible to various problems that can eventually lead to their demise.
Managing bagworm infestations involves several methods, from manual cocoon removal to supporting natural predators and, as a last resort, using chemical control. However, the most effective strategy to protect trees from these harmful pests is to proactively prevent infestations by maintaining healthy vegetation, proper tree spacing, regular inspections, and proper maintenance practices.
Like the case carriers of Gelechioidea, which is the basal lineage of Ditrysia, bagworms are members of the superfamily Tineoidea.
With only 1,350 species, the family is relatively small and widespread practically everywhere.
These insects are actually moths, not worms, despite their name, which refers to the worm-like form of the larvae.
Bagworms weave together pieces of leaves and silk to create their protective cocoon, which they inhabit throughout their life cycle. The larvae use a thread that resembles silk to attach fragments of plant debris, such as leaves, twigs, and bark, to their bodies to create these bags. The bag also gets bigger with them.
The eggs of the female moth hatch in late spring or early summer.
When the moth is ready to mate, only the adult male leaves the safety of its pouch; the female remains in the bag.
Bagworms, typically infesting evergreen and deciduous trees, can sometimes be missed at first glance due to the similarity of the bags they create.
In the absence of these favored hosts, poachers will consume the leaves of almost any tree, including fir, spruce, pine, hemlock, gum, sycamore, acacia, and acacia. Their favorite host plants are cedar, hemlock, juniper, and false cypress.
Despite their seemingly harmless appearance, poachers cause serious damage to trees. The problem is hiding them until the infestation gets worse.
They make it difficult for the tree to photosynthesize and produce the nutrients it needs to grow and survive by eating the leaves of the tree.
At the same time, they weaken the tree, increasing its susceptibility to diseases, pest attacks, and environmental stress. The tree may eventually die if the bagworm infestation is not treated.
There are several different ways to deal with bagworm infestations. Below we explain a few of them.
Removing each bag/cocoon from the tree one at a time is one method. However, if fewer trees were affected, it might be feasible. This is not the best approach if you have a landscape full of affected trees, each of which has several bags of burrs.
Fortunately, there are alternative techniques such as
In case of extensive infestation, affected branches should be pruned and destroyed appropriately. In addition, search nearby fences and other areas of potential infestation.
Encourage natural predators: Several birds and parasitic wasps are known to consume bagworms, so it can be helpful to attract their attention when dealing with bagworms. One bird that can break open the bags and consume the females or eggs inside is the woodpecker. Promoting this approach and making your farm or yard bird-friendly will help you avoid using chemicals that would also kill beneficial insects.
Chemical Control: Use acephate (Orthene), cyfluthrin, and spinosad sprays for chemical control if all other methods fail. It is important to remember that chemical control should only be used as a last resort and with extreme caution due to the potential effects on the environment. If chemical control is chosen, apply on a dry, windless day to ensure the product dries quickly and is not blown away by the wind.
The best solution is to prevent bagworm infestation in the first place.
This can be achieved by, among other things, monitoring the surrounding vegetation, planting trees at the correct distance from each other to prevent overcrowding, routine tree inspections, and proper maintenance.
Bagworms, often mistaken for worms because of their name, are actually moths known for their protective cocoons made of plant debris. Their seemingly innocuous appearance belies the significant damage they can cause to trees by preventing photosynthesis and weakening them, making them vulnerable to various threats. Management of bagworm infestations involves several approaches, from manual removal and pruning of affected branches to the promotion of natural predators and, as a last resort, the use of chemical control. However, the most effective strategy remains prevention, which includes vigilant monitoring, proper tree maintenance, and providing a healthy environment that repels these pests. Vigilance and early intervention can save trees from the harmful effects of bagworm infestation and ensure their continued growth and vitality.