Bagworms on Cedars: How to Save Your Missouri Evergreens
If you look closely at your Cedar, Juniper, or Arborvitae trees and see what looks like little pine cones hanging from the branches—look closer.
If they move, you have Bagworms.
These are not cones. They are silken bags covered in dead needles, and inside each one is a caterpillar that is eating your tree alive.
Why Are Bagworms So Bad?
Bagworms are voracious eaters. A heavy infestation can strip a Cedar tree of all its needles in a single summer.
- Evergreens don't bounce back: Unlike Oak trees, which can grow new leaves if eaten, an evergreen that is stripped bare will usually die.
The Lifecycle (Timing is Everything)
1. Winter (The Eggs)
The bags you see in winter are filled with hundreds of eggs. The female moth dies inside the bag, leaving her eggs for next year.
- Action: Hand Picking. If the tree is small, just pull the bags off and drown them in a bucket of soapy water. Do not just throw them on the ground; the eggs will still hatch.
2. Late May - June (The Hatch)
The eggs hatch, and tiny microscopic caterpillars emerge. They spin a small silk thread and "balloon" to nearby trees.
- Action: Spray Time. This is the ONLY time chemical sprays work effectively. The worms are small and haven't formed their thick protective bags yet.
3. August (The Armor)
By late summer, the worms have built thick bags made of needles. Sprays barely touch them now.
- Action: It's too late for spray. You have to wait until winter to pick them off or risk the tree dying.
Can the Tree Be Saved?
If your tree is brown and see-through:
- Scratch Test: Scratch a branch. If it's green underneath, there is hope. Water it heavily.
- Brown & Brittle: If the branches snap, it's dead. We need to remove it before it becomes a fire hazard.
Protect Your Privacy Screen Cedars are often used as windbreaks or privacy fences. Don't let bagworms open a hole in your wall.