If you’re dealing with a bagworm problem, you’re in luck: you’ve got nature on your side!
There are multiple predator species that will eat bagworms for you! Ichneumon wasps, woodpeckers, and sapsuckers all consume bagworms.
By knowing the natural predators of this caterpillar, you can create specific control methods by avoiding killing the insects that help you by indiscriminately using pesticides.
Bagworms do not pose a danger to humans, consider it a pest, and can mostly be damaging by defoliation, it’s definitely something worth understanding if you want to keep numbers down.
In this article we are going to go over the nitty gritty of recognizing and responding to these interesting pests, including all of the insects and birds that eat bagworms.
What Are Bagworms?
Bagworms are the unique larvae of the bagworm moth, a Lepidoptera family has about 1300 sub-species, all of which develop their own unique bags or casings to live in.
The Bag of the Bagworm
Last of all, the hatching eggs are left in the bag of the bagworm that took the time to lay them.
Once they hatch off they go by ballooning. Each young caterpillar spins a silk strand (a parachute) to catch the wind and will take off to the new host plant. They would be following at least a few last hosts nearby but the ballooning process will occur a few times until a host is found.
The larvae are bagworm moths laying those eggs and when they are in their initial pupal earnest they make these bags by bonding the plant material they selected in combination with the silk they are spinning to make a combination that resembles a large sock or sleeping bag.
The unique things they made it with include pine needles, leaves, twigs and other plant material. The bag serves as blank canvas so they camouflage while they are feeding on the host plant.
Did you know? as they lay on and in the bag only their head and thorax are seen outside of the bag, so they drag it around while eating, and can retreat into it in case of a predator.
The Bagworms Bag Is Also the Location of Metamorphosis
When ready for metamorphosis, bagworm larvae will attach their bag to a bare branch, enter it and pupate.
Female adult bagworms are wingless, they continue to live in the bag and dump eggs inside their bag for next year’s larvae that will overwinter and emerge in the spring.
Males will emerge from their bag as moths that look more “typical”.
Their adult lives are short, females live a couple weeks, the males only a few days.
When Their Numbers Are High, Bagworms Can Do a Lot of Harm to Surrounding Vegetation
Since bagworms feast on their host plants and trees, large populations of caterpillars and adult females can do a lot of damage.
They can completely defoliate plants and trees as bagworm population spreads from infested plant to infested plant.
What Do Bagworms Eat?
Bagworms have the ability to munch on the leaves of any tree.
While deciduous trees may be able to recover after they are defoliated, evergreen trees cannot and will almost certainly die if bagworms infest them.
Bagworms, in order to thrive, prefer the following kinds of deciduous and evergreen trees:
- Pine
- Fir
- Spruce
- Sycamore
- Sweetgum
- Honey locust
- Black locust
- Maple
- Juniper
- Linden
- Boxelder
- Cypress
- Arborvitae
The Activities of the Bagworm Are a Big Problem to Us Landowners
Thyridopteryx ephemeraeformis is a bagworm you find in North America.
In the northern states, frost usually kills overwintering eggs, but further south the eggs and larvae can survive, and populations can take root.
Bagworms are often introduced into new locations on nursery stock or saplings that are installed as landscaping.
They may reproduce rapidly to damage the new trees, and if winter is mild, they may produce rapidly and damage trees.
Little known fact: Each female bagworm can produce up to 1000 eggs, meaning that population explosions can occur.
Strategies for Tackling Bagworm Infestation
You can definitely control bagworms with a strategic, concerted effort towards eradication.
The most important thing to do is know how to identify the “bags” or bagworms and then treat them before they increase in numbers.
Here are the important organic control options for bagworm caterpillars and moths:
- Handpicking: If you can identify the overwintering egg-filled bags, you can wipe out the bagworm population by severing the bags from the attachment point and placing them in a bucket of soapy water. A handpick can also deal with the caterpillar and female moths if not abundant.
- Bt treatment: Bacillus thuringiensis (Bt) spray can kill the small bagworm caterpillars that emerge. This endotoxin insecticide ruptures the gut of the caterpillar when eaten.
- Spinosad: Spinosad is another insecticide (a neurotoxin) that has shown to be effective against bagworm infestations. It is best applied during the young caterpillar stage.
Encouraging Natural Predators Is an Effective Long-term Approach for Dealing with the Bagworm
Natural enemies of the bagworm caterpillar, such as the ichneumon wasp, vespid wasp, hornets, birds (chickadees, nuthatches, sparrows, woodpeckers, sapsuckers, and titmice) are one of the most effective ways to manage populations of this pest.
Some common insects and animals that will eat bagworms:
- Ichneumon wasps
- Vespid wasps
- Hornets
- Chickadees
- Nuthatches
- Sparrows
- Woodpeckers
- Sapsuckers
- Titmice
You may attract parasitic wasps, including the ichneumon wasp, to areas infested with bagworms by planting Aster plants close to the affected tree. The attractive flowers will draw in the wasps, which will parasitize bagworms by depositing eggs within them.
Rounding Up
Bagworm’s armor may seem like it makes them invincible but they are not, just remember, a collective effort to hit them while they are young is what will keep this all-american pest in control.