Bagworm
Scientific Name: Thyridopteryx ephemeraeformis (or other species within Psychidae)
Order & Family: Lepidoptera, Psychidae
Size: Larval case (what is pictured) can range from 1/4 inch to over 2 inches (6 mm - 5 cm) depending on the species and larval stage. The adult males are small moths, while adult females are wingless and remain inside the bag.
Natural Habitat
Found on various trees and shrubs, including conifers (e.g., cedar, juniper, pine, spruce) and deciduous trees (e.g., maple, oak, sycamore). They are typically found in gardens, orchards, and forested areas.
Diet & Feeding
Bagworm larvae are herbivorous, feeding on the foliage of their host plants. They chew holes in leaves or needles, causing defoliation.
Behavior Patterns
The most distinctive behavior is the construction of a protective silk case (bag) covered with vegetation pieces (leaves, twigs, bark). The larva lives, feeds, pupates, and overwinters inside this bag. Adult males are winged moths that emerge to mate, while adult females remain wingless and larval-like inside their bags, laying eggs there before dying.
Risks & Benefits
Risks: Bagworms are considered pests, especially when their populations are high, as they can cause significant defoliation and even death of host trees and shrubs, particularly evergreens. Benefits: In natural ecosystems, they can be part of the food chain for birds and other predators, but their impact as a benefit is generally minor compared to their potential as a pest.
Identified on: 10/30/2025