Leaf Rollers

Identification

Size: Most measure between 0.5 to 1 inch (12 to 25 millimeters) in length.

Color: A range of colors and patterns, including shades of gray, brown, yellow, or white

Description: Leaf rollers, commonly found on ash and aspen trees, are small caterpillars that create cocoons by rolling leaves into tube-like structures. When unrolling an affected leaf, you can observe the caterpillar, webbing, fecal matter, and eggs inside. In early to mid-June, the caterpillar uses a silk line to migrate to a new leaflet, where it folds the leaflet into a cone shape and forms its cocoon. In the fall, the adult emerges as a small gray moth with a 12 mm wingspan.

Leaf rollers are a diverse group of moths and caterpillars belonging to various families, with the most common ones found on ash and aspen trees. Their life cycle comprises four stages: egg, larva (caterpillar), pupa, and adult (moth).

Egg: Adult moths lay their eggs on the surface of leaves or within plant tissues during late spring or early summer, depending on the species. The eggs are small, oval-shaped, and often laid in clusters. They hatch within a week or two, depending on environmental conditions.
Larva (caterpillar): Upon hatching, the tiny caterpillars begin feeding on the plant’s leaves. As they consume the foliage, they create a unique cocoon by rolling the leaf into a tube-like form, securing it with silk threads. Inside this rolled leaf, the caterpillar is protected from predators and weather elements. The larval stage lasts for several weeks, during which the caterpillar grows and molts, shedding its old skin several times to accommodate its increasing size.
Pupa: In early to mid-June, the fully-grown caterpillar migrates on a silk line to a new leaflet, where it folds the leaflet into a characteristic cone shape and forms its pupa or cocoon inside. The pupal stage is a resting phase, during which the caterpillar undergoes metamorphosis, transforming into an adult moth. The pupal stage typically lasts for several weeks to a month or more, depending on the species and environmental conditions.
Adult (moth): In the fall, the adult moth emerges from the pupa. Adult leaf roller moths are small, with wingspans ranging from 0.5 inch (12 millimeters) to 1.5 inches (38 millimeters), and can be gray, brown, yellow, or white, often with intricate patterns on their wings. After emerging, the adult moths mate, and females lay their eggs on host plants, completing the life cycle and starting a new generation.

While leaf rollers can cause significant damage to the appearance of plants, they typically do not kill the plant outright. However, their presence can reduce the plant’s vigor, making it more susceptible to other pests and diseases.

Identifying leaf rollers involves observing their unique behavior, the damage they cause, and their physical appearance in different life stages. Here are some key indicators to help you identify leaf rollers:

Rolled or folded leaves: Look for leaves that are rolled, folded, or webbed together, often held in place with silk threads. This is a telltale sign of leaf roller activity, as they create these protective shelters while feeding.
Leaf damage: Examine leaves for signs of feeding damage, such as irregular holes or chewed edges.
Larvae (caterpillars): Leaf roller caterpillars are typically green, brown, or yellowish in color, measuring about 0.5 to 1 inch (12 to 25 millimeters) in length, depending on the species. If you unroll an affected leaf, you may find the caterpillar, webbing, fecal matter, and sometimes eggs inside.
Pupal cases: Look for the characteristic cone-shaped, folded leaflets where the caterpillar pupates. Pupal cases may be found on the tree or on the ground around the tree.
Adult moths: Adult leaf roller moths are small, with wingspans ranging from 0.5 inch (12 millimeters) to 1.5 inches (38 millimeters). Their color can vary from gray, brown, yellow, or white, often with intricate patterns on their wings.

By observing these signs and the physical appearance of the insects at various life stages, you can identify leaf rollers and take appropriate action to manage them.

If you suspect leaf roller infestations, look for the following signs: rolled or folded leaves held together with silk threads, leaf damage such as irregular holes or chewed edges, green or brown caterpillars inside the rolled leaves, and silk webbing and fecal matter within the affected foliage. Additionally, you may observe cone-shaped pupal cases on the tree or ground and adult moths with varying colors and patterns on their wings. These indicators can help you confirm the presence of leaf rollers and take appropriate action.

To prevent leaf rollers from infesting your trees and plants, consider the following strategies:

Maintain plant health: A healthy plant is more resistant to pests. Ensure proper watering, fertilization, and pruning to maintain the overall health of your trees and plants.
Regular monitoring: Inspect your plants routinely for signs of leaf rollers, such as rolled or folded leaves, leaf damage, or the presence of caterpillars.
Hand removal: For small infestations, you can remove the rolled leaves, caterpillars, or pupae by hand and dispose of them in a sealed bag or container.
Encourage natural predators: Attract beneficial insects, such as parasitic wasps, lacewings, and ladybugs, by planting a variety of flowering plants in your garden. These predators can help control leaf roller populations.
Pheromone traps: Use pheromone traps to monitor and control adult moth populations. These traps attract male moths, reducing the chances of mating and egg-laying.
Pest control: If infestations are severe, consider using a professional pest control company. A trained professional can apply effective pest control methods that minimize harm to beneficial insects and the environment.

By implementing these preventive measures and monitoring your plants regularly, you can effectively reduce the risk of leaf roller infestations and maintain the health of your garden or landscape.