Gypsy Worms

Identification

Size: Gypsy worms, also known as gypsy moth caterpillars, can vary in size depending on their developmental stage. Early instar caterpillars are typically small, measuring around 1-2 centimetres (0.4-0.8 inches) in length, while mature caterpillars can reach up to 6 centimetres (2.4 inches) or more.

Color: Gypsy worm caterpillars have a distinct appearance. In their early instar stages, they have blackheads and are covered in long, bristly hairs. As they mature, their bodies develop a variety of colour patterns, ranging from dark brown or black to lighter shades of gray, tan, or brown. They often display a series of five pairs of blue dots followed by six pairs of red dots along their backs.

Description: Gypsy worms are moth caterpillars that belong to the Lymantria dispar species. They are native to Europe and Asia but have been introduced to various parts of North America. These caterpillars are voracious feeders and are known for defoliating trees and shrubs.

The Gypsy Moth caterpillar, scientifically known as Lymantria dispar dispar, is a notorious forest pest native to Europe and Asia but has established itself in North America. These caterpillars are voracious defoliators, posing a significant threat to trees and ecosystems. They go through several stages of development, marked by distinct physical changes. Their presence is recognized by five pairs of blue dots followed by six pairs of red dots along their back, and they are known for their capacity to strip foliage from trees, causing substantial damage to forests and shade trees across their range. Effective management strategies are essential to mitigate their impact and protect vulnerable ecosystems.

Identifying gypsy worms can be done through several distinguishing characteristics:

Caterpillar appearance: Look for caterpillars with hairy bodies and distinct colour patterns. They have a characteristic pattern of blue and red dots along their backs, especially in later instar stages.
Feeding behaviour: Gypsy worms are known to feed on a wide range of trees and shrubs. If you notice defoliation on your plants, particularly oaks, birches, aspens, or other deciduous trees, it could be an indication of gypsy worm infestation.
Egg masses: Gypsy worms lay their eggs in tan-coloured, fuzzy masses that can be found on tree trunks, branches, or other surfaces. These egg masses are often covered with protective hairs and can contain hundreds of eggs.

Defoliation: Gypsy worms are notorious for defoliating trees and shrubs. If you observe significant leaf loss and bare branches in your landscape, it could be a sign of gypsy worm infestation.
Presence of caterpillars: Look for the presence of gypsy worm caterpillars on your plants. They are often seen crawling on tree trunks, branches, or foliage, especially during their active feeding periods.
Silk threads: Gypsy worm caterpillars spin silk threads as they move between branches or descend from trees. These threads may be visible, especially during heavy infestations, and can hang down from tree canopies.

While it can be challenging to prevent gypsy worm infestations entirely, there are some steps you can take to minimize their impact:

Inspect and remove egg masses: Before the hatching season (usually in late spring or early summer), inspect your trees and remove any gypsy worm egg masses you find. Destroy the egg masses by scraping them into a container filled with soapy water or by double-bagging and disposing of them.
Maintain tree health: Healthy trees are more resilient to gypsy worm feeding. Provide proper watering, regular pruning, and fertilization to ensure your trees are in optimal condition.
Implement physical barriers: Use sticky bands around tree trunks to trap caterpillars as they crawl up or down the trunk. This can help reduce the number of gypsy worms reaching the foliage.
Consider biological controls: Natural enemies, such as parasitic wasps or viral and fungal pathogens, can help control gypsy worm populations. Consult with local agricultural extension services or arborists to determine suitable biological control options for your area.