June 25, 2009
During late June and July, you seem to notice a loss of needles on your evergreens, and an increase in cone-like structures hanging from the branches. Upon closer inspection, you realize the cone-like structures are actually moving, and devouring your evergreen’s needles! The culprit – the common Bagworm.
Description – Bagworms are caterpillars that during June, July and early August, make distinctive spindle-shaped bags comprised of leaves, needles, sticks, bark, etc, and actually live inside the bag (mature bags can reach 1 ½ to 2 inches long). They carry it with them as they move around both deciduous plants and evergreens feeding on the foliage. They are especially damaging to evergreens (juniper, spruce, pines, arborvitae, cedar, cypress, etc.) as stripping the plants of their foliage may result in death of the plant. And they largely go unnoticed as they do resemble pine cones! The female remains in the caterpillar form, but the male eventually develops into a winged bee like creature (August). He mates with the female, resulting in the fertilized female laying from 300-1,000 eggs in her bag. The bag is then attached to a plant branch with a silk-like band, to hang in place over winter. Those eggs over winter in that bag, and hatch out late May and early June, starting the entire bagworm process all over again. These tiny bagworms are so small, they are carried in the winds to other evergreens (ballooning stage) or they may stay on the plant where they hatched.
Control:
1.) Hand Picking – Physical removal is a great way to rid your plants of bagworms. Whether during the feeding times or over the winter and early spring before the eggs hatch (which happens late May thru mid June), picking the bags off the plants and destroying them stops the bagworms before they ever get started. Destroy the bags by smashing, soaking in soapy water, or burning.
2.) Chemical Control – There are no preventative sprayings for preventing bagworm infestations. You can only spray for control after the bagworms have been noticed actively feeding on the plants. Bt (Bacillus thuringiensis) and Captain Jacks Deadbug Brew are very effective against the early stages of bagworms, and very much environmentally safe. Spray these towards mid to late June after all bagworms have hatched. Other insecticides will also control bagworms, and remember that earlier sprays against younger larvae are more effective rather than later against older larvae. And the silk bags will become an impermeable protectant for the bagworm, so spraying means making sure the foliage is soaked. Orthene, Eight, Sevin, Malathion, Rotenone, etc are a few of the many insecticides listed for bagworm control. For all sprays, two applications may be needed for total control. If you do not realize that there is a bagworm problem until late in the season, forget the sprays. Hand pick what you can, and wait until next mid June to spray the newly hatched bagworms when they are most susceptible to sprays. Use this tactic for controlling bagworms in the tops of tall evergreens that cannot be hand picked. Wait for hatching, and then spray as needed.
Tags: bagworms, evergreens
