**Underwing Moths** (*Catocala* spp., Family Erebidae) are large, striking moths, generally named for the brightly colored (red, yellow, orange) bands or patches on their hindwings, which are hidden when the moth is at rest. The conflict is **defoliation of shade trees**: while most species feed on deciduous trees, some can cause noticeable defoliation, particularly to **hickory, walnut, oak, and willow** trees, by the activity of their large, cryptically colored caterpillars.
Taxonomy and Classification
Underwing Moths belong to the Order Lepidoptera (Moths and Butterflies). They undergo complete metamorphosis. They are one of the largest genera of moths, primarily inhabiting North America.
Physical Description
Adult wingspans range from 50\text{ mm} to over 100\text{ mm}.
- **Adult (Key ID):** Forewings are camouflaged (bark-like gray/brown); hindwings (underwings) feature striking, bold patterns of red, orange, or yellow bands contrasting with black.
- **Larva (Key ID):** Large, cryptic, twig-like caterpillars with irregular growths or filaments that aid camouflage; they rest flat against tree bark during the day.
- **Behavior ID:** When disturbed, the moth flashes its brightly colored hindwings as a “startle display” (flash coloration) to deter predators.
- **Conflict:** Ornamental (Minor Defoliation).
Distribution and Habitat
Found primarily across North America, Europe, and Asia. Habitat is deciduous forests and urban/suburban areas with mature shade trees, often resting low on the trunk bark.
Behavior and Conflict
The conflict is highly localized and usually minor.
- **Nocturnal Feeding:** Caterpillars feed at night and hide during the day, making damage often noticed before the pest is seen.
- **Tolerance:** Damage is usually well-tolerated by mature trees unless combined with other stressors.
Management and Prevention
Management is **Monitoring and Conservation**.
- Checking tree trunks for resting larvae in the spring; infestations are usually managed naturally by birds and parasites.
- Chemical control is rarely warranted, but targeted application of *Bacillus thuringiensis* (Bt) can control high populations of small larvae on high-value trees.
Conservation and Research
Underwing Moths are often collected and studied by entomologists for their unique camouflage and flash coloration. Research focuses on their biodiversity and role in forest ecosystems.