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Bagworm Moths: Everything You Need to Know

All About Bagworm Moths

In the realm of garden and tree care, bagworm moths present a notable challenge. This article focuses on unraveling the life cycle of these pests, starting from their initial phase as minuscule caterpillars to their development into moths. We’ll guide you through identifying these pests, understanding their preferred hosts, and importantly, provide effective strategies for controlling and preventing their infestations.

Bagworm Moth Bag

Overview of Bagworm Moths

Identification of Bagworms
Bagworms represent the caterpillar phase of moths. In North Carolina, they typically hatch in May and create a tiny cocoon, about 1/8 inch in length, adorned with plant fragments from their host plant. On closer inspection, you can observe their movement as they consume the plant. Bagworms roam freely for feeding, taking their bags along. As the summer progresses and the caterpillar grows, the bags expand to accommodate their increasing size.
Preferred Plants and Habits
Bagworms commonly infest conifers like junipers, spruces, and pines. They are also found on deciduous trees such as maples and oaks. These moths prefer plants with ample foliage, providing both food and camouflage for their bags. Bagworms can strip a plant of foliage in a matter of days if the infestation is severe. If you notice your shrub or tree rapidly turning brown, take a closer look at the plant- bagworms are excellent at camouflage.
Treating Infested Plants
Physical Removal: Handpick bags in winter or early spring before larvae emerge. Biological Controls: Encourage natural predators like birds or introduce parasitic wasps. Chemical Treatments: Apply Bacillus thuringiensis (Bt) or insecticides like permethrin when larvae are young and actively feeding, typically in late spring to early summer.
Photo Credit: R Malloy UME

Interesting Facts about Bagworms

  • Bagworm Moth females are wingless and remain in their bag for their lifespan, while males have wings to search for mates.
  • Bagworms have a 10 month lifespan, spending most of their lives as caterpillars in their bags.
  • Bagworm Caterpillars always carry their bag with them, using it for camouflage and protection.
  • Bagworms produce silk, using it to create their bags, attach to plants, and to fly in the wind, moving from plant to plant.
Young Bagworms on Juniper
Bagworm larvae create a bag right after they hatch in the spring. Young Bagworm caterpillars are extremely small, hatching at a size of 1-2 mm. As they feed, Bagworm larvae will reach a size of up to 2 inches before they pupate in the fall.

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