Do Bagworms Attack Knockout Roses?

Identification

• Bagworms are small, pale-green caterpillars that feed on leaves. They are common problems in trees such as pines, junipers, cedars, and spruces but also have attack rose bushes. Spotting one of the bags their lifecycle revolves around is the best identification method. Bagworm eggs are deposited in a small bag made of leaves and other plant parts. They remain secured away until hatching. As larvae and later as adults, they use the bag as home, making it larger when necessary and eating foliage from it. These bags are about 2 inches in length, and are brown or greenish depending on the plant parts used in their construction. They hang from foliage.

Damage

• The bagworm is not as serious a threat as other knockout rose pests because their numbers rarely rise high enough for significant damage. When present in large enough populations, bagworm damage is extensive. As they eat the leaves of the knockout rose plant, holes appear and later leaves begin to fall away. They plant may eventually lose all of its leaves. In a severe case, the knockout rose plant may die.

Prevention

• Preventing bagworm damage to knockout roses begins with daily inspections. At the first sign of damage to leaves, look for the bags and caterpillars. Pick them away by hand. Destroy the bags. If eggs have not hatched, this prevents an infestation.

Control

• If eggs slip by the daily inspection and an infestation does arise, manage the bagworms with a good insecticide applied at the right time. Use an insecticide no later than when the bagworms reach the larval stage. This is typically in the early part of the summer.