Archive for Monday, July 6, 2009


Eliminate bagworms before they eliminate your evergreens

July 6, 2009


Thyridopteryx ephemeraeformis, commonly known as bagworms, will quickly destroy evergreens and shrubs when left untreated.

Thyridopteryx ephemeraeformis, commonly known as bagworms, will quickly destroy evergreens and shrubs when left untreated.

If you have evergreens in your landscape, you are most likely familiar with bagworms. Bagworms are small caterpillars that feed off needles and leaves, stripping plants of their foliage and causing trees and shrubs to die. Bagworms are easily identifiable by the 1-inch to 2-inch spindle-shaped sack they live in. The sacks are commonly mistaken for small pinecones as they hang from the underside of plant foliage.

Now is the time to inspect your evergreens for bagworms. If you find spindle spindle-shaped sacks covered with decaying foliage, you will want to take immediate action before any further damage is done to your plants.

Step 1: Use scissors or pruning shears to remove as many bags as possible. Plucking them off by hand will leave a silken string that could do further damage to the foliage.

Step 2: Rake up any plant debris or leaves from the surrounding area to help prevent future infestation.

Step 3: Use a tank sprayer or hose-end sprayer to apply a mixture of water and bacillus thuringiensis, commonly referred to as BT. BT is a natural bacteria that affects leaf- and needle-feeding insects. It is safe for use around kids and pets and can even be used on food crops.

Step 4: Continue to spray affected foliage weekly until all signs of larvae have disappeared.

If the bagworm infestation is aggressive and BT does not seem to do the trick, there are several chemical products that can also be used to control bag worms. The most affective of these is Sevin, which comes in both a liquid and powered form. Be sure to read the manufacturer’s instructions before applying any product to your plant life.


farmgal 8 years, 11 months ago

Have used the BT in the past. Doesn't seem like anyone carries it anymore. Anyone know of a local place that still carries BT?

JohnBrown 8 years, 11 months ago

This article would have been more timely three weeks ago. Mid-June is the time to spray BT, when the critters are tiny. recommend two sprayings, one on June 15th and the other on June 25th.

It's still not too late to spray since this was a cool spring and the bagworms are behind schedule.

VTHATC2 5 years, 12 months ago

Will the use of BT harm birds that are nesting in the affected shrubs?

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