Bagworms can wipe out your expensive evergreen landscaping in a single season if left uncontrolled. If you own a home and have landscaped with juniper, arborvitae, spruce, pine or cedar, don’t let the bagworms cost you a fortune. I’ve seen it happen to my neighbors. They plant some really nice foundation evergreen bushes and think they are done. They never check to watch for problems and soon there are little sacs hanging from the bushes. In a couple of months, the worms have completely stripped the leaves, killing the plants.
What are bagworms?
Bagworms, Thyridopteryx ephemeraeformis, are moths that live in a silk bag covered with plant debris.
Around here, we find them mainly on cedar trees. They attach an oblong sac to a tree twig by a silk strand and come out to eat the leaves of the tree. The male is the only sex that actually becomes a moth. His body is black and furry with feathery antennae and inch long transparent wings. The poor female bagworm gets inseminated, lays eggs and then dies – spending her entire life inside the bag looking like a soft-bodied yellow-white maggot. Note to self: don’t get reincarnated as a female bagworm!
Where do bagworms live?
Canadian readers may not have to deal with this pest, but those in the US do – especially in the midwest. From Nebraska to the Atlantic and from Southern Michigan to Argentina, bagworms thrive.
How do you get bagworms on your trees?
Birds eat the bags and the eggs have hard enough shells to pass through the bird’s digestive system intact.
“Their dispersal over wide areas occurs mainly through movement of infested nursery stock and ornamental plants, or by ballooning (wind dispersal) of small bagworm larvae during early June.”
What is the lifecycle of a bagworm?
Right now, in February, the little eggs are safely ensconced in their bags for the winter. Come May, the hungry little larvae are going to be crawling out and nibbling on your trees!
From May through August or early September, those larvae are feeding, growing and enlarging their bags as they grow. You will see signs of leaf damage and perhaps dying trees. If they manage to strip all the leaves off the tree they stared with, the larvae drop off the tree and crawl to another to get food.
The larvae attaches it sac to a small branch, leaving the bottom open to pass it’s waste and the top open so it can crawl out to feed. It can drag that bag around if need be.
In the fall, the male pupae emerge from their bags and search for those immobile females waiting inside their bags for their mates. The female lays hundreds of eggs inside the bag and then dies. The cycle starts over, with the eggs hanging out in the bags until spring.
How can you control your bagworms organically and cheaply?
The way we control ours, and the method I suggest to you is work intensive and manual. The cost is a bit of your time and possibly a few bucks to buy some kerosene or gasoline or other lighter fluid.
Periodically inspect your bushes and trees for signs of bags. When you find them, clip or pluck (wearing gloves cause the worms are yukky and the bags are squishy) the bags from the plant and place in a metal can or bucket. Once you have collected all the worms you can see, pour some gasoline over them and light a fire. You want to totally destroy the bagworms inside their bags and burning them is the most effective way to do so. If you leave the bucket for later, be sure to seal it so the bagworms can’t escape. They will crawl up the metal surface and try to get out.
We have gotten up to a gallon of bagworms from our trees at a time in years with heavy infestations.
Follow up by raking the ground under the infested bush or tree to find any bags that have dropped to the ground, and then destroy those as well.
Keep checking the greenery as you will miss some of the little sacs (they can be hard to see, especially in the spring when the leaves embedded in the bag are still green). We check once a week or so after finding bagworms.
The next year, you may find that you are re-infested and may need to repeat the procedure.
Obviously, if the bagworms are very high on the tree and you can’t get to them to pick them off, you may need to take non-organic and more expensive measures to kill the bagworms.
Have you dealt with bagworms? How did you handle the situation?