Bagworm Life Cycle: Unraveling the Mysteries of Nature’s Architects

Bagworms are fascinating creatures with a unique life cycle that impacts a variety of plants and trees.

From their intricate protective cases to their feeding habits, understanding the bagworm’s life cycle can help to better control infestations and protect vegetation in residential and commercial settings.

The bagworm’s journey begins early in June when they hatch from eggs that overwintered in the old bags attached to tree branches.

Upon hatching, these young caterpillars immediately start spinning their own bags, which they enlarge as they grow and feed on nearby plants.

Preferring to feed on conifers like arborvitae, cedar, juniper, and pine, bagworms can also attack deciduous trees such as sycamore, maple, locust, boxelder, and linden.

By recognizing and understanding the bagworm’s life cycle, we can better protect trees and shrubs from these voracious feeders and maintain the health and beauty of our landscapes.

Overview of Bagworm Life Cycle

Egg Stage

The life cycle of a bagworm begins with the egg stage. Female moths lay eggs inside their bag-shaped pupal case.

Each bag can contain about 300 to 1,000 eggs. These eggs usually overwinter and hatch in late spring or early summer.

Larval Stage

When the eggs hatch, bagworm larvae emerge and start feeding on nearby host plants. As they grow, these caterpillars create unique cone-shaped bags from silk and various debris, such as leaves and twigs.

The bag grows with the larva, reaching a size of 1/4 inch to over 2 inches depending on its stage of development. The larval stage lasts for a few months.

Pupal Stage

After they are fully grown, the bagworm larvae enter the pupal stage. At this point, the caterpillars attach their bags to the host plant and seal the opening.

During this stage, bagworms undergo metamorphosis and transform into adult moths. The pupal stage usually lasts 7 to 10 days.

Adult Stage

In the adult stage, male and female bagworms have distinct forms. Male moths are small, bee-like insects with clear wings, while female moths are wingless, legless, and remain inside their bag.

Mating occurs when the male moth finds a female by following the pheromones released by her. After mating, the female dies and her bag serves as an egg repository, continuing the cycle.

Here is a comparison table of male and female adult bagworms:

Overall, the bagworm life cycle consists of four main stages: egg, larval, pupal, and adult stages.

From starting as an egg within the female’s bag, hatching into a caterpillar that feeds on host plants, pupating, and turning into either a male or female adult moth, this unique insect has a fascinating life cycle.

Biology and Behavior

Reproduction

Bagworms (Thyridopteryx ephemeraeformis) reproduce in late summer and early fall. The wingless females stay inside their bags, while the males transform into brown, fuzzy moths that can fly¹.

Mating occurs when the male enters the female’s bag where she deposits her eggs².

Feeding Habits

Bagworm caterpillars are most active from June to September, when they emerge and start to feed on both evergreen and deciduous trees.

For example, pine, juniper, and cedar are some of their favored evergreens, whereas deciduous trees such as maple, sycamore, and linden can also be targeted³.

Initially, these caterpillars can be found munching on leaves or needles⁴, but as they grow, they cause considerable damage to branches, leading to browning or foliage loss⁵.

Migration and Dispersal

Upon hatching, bagworm larvae disperse by crawling or getting carried away by the wind.

They construct a small bag, made from silk and plant materials, which they enlarge as they grow⁶.

As larvae move from one plant to another, they bring their bags along, infesting new areas.

Geographical Range

Bagworm moths are native to the eastern half of the United States².

They can cause serious damage to a wide range of ornamental shrubs and trees in this region. Some commonly affected plants include:

• Conifers (e.g., arborvitae, cedar, juniper, and pine)
• Deciduous trees (e.g., sycamore, maple, locust, boxelder, and linden)

Their prevalence increases in urban settings and isolated trees, often escaping detection until significant plant damage has occurred³.

Conclusion

Bagworms are found in many regions of the world, where they feed on various plants. Their life cycle consists of four stages: egg, larva, pupa, and adult.

The eggs are laid inside the female bag and overwinter on the host plant. The larvae hatch in spring and start making their own bags as they feed.

The larvae pupate inside the bags in late summer or fall. The adult males emerge as winged moths and mate with the wingless females inside their bags. The females die after laying eggs and the cycle repeats.

Footnotes

1. University of Nebraska-Lincoln ↩ ↩²
2. Ohio State University ↩ ↩²
3. University of Maryland Extension ↩ ↩²
4. Purdue University ↩
5. University of Delaware ↩
6. Ohio State University ↩