Lichen moths are a diverse group of small moths whose caterpillars primarily feed on lichens and algae growing on trees, rocks, fences, and other surfaces. Most lichen moths are harmless to people and property, and many species are considered indicators of good environmental conditions because lichens are sensitive to air pollution. Learning how to recognize lichen moths—and understanding their life cycle and habitat needs—can help prevent misidentification and unnecessary pest treatments.
Identification & Appearance
Adult lichen moths are typically small to medium in size with narrow wings and a slender body. Many species are gray, tan, cream, or brown, blending in against lichen-covered bark and stone. Others are more brightly patterned with yellows, oranges, or reds, sometimes paired with dark markings that may discourage predators.
Lichen moth caterpillars are usually elongated and may appear lightly fuzzy or bristly. Because their food source grows on surfaces rather than on leaves, larvae are often found on tree trunks, branches, shaded rocks, wooden fencing, or exterior walls where lichens and algae are established.
Taxonomy & Classification
Lichen moths are commonly associated with the subfamily Lithosiinae within the family Erebidae (order Lepidoptera). Historically, many were grouped with tiger moths, but modern classification typically places them within Erebidae. Because this is a large and diverse group, “lichen moth” is often used as a broad common-name category rather than a single species.
Life Cycle
Lichen moths undergo complete metamorphosis with four life stages: egg, larva (caterpillar), pupa, and adult. Timing and number of generations per year vary by species and climate, but the overall pattern is similar across the group.
- Eggs: Laid on or near lichen- or algae-covered surfaces such as bark, rock, or weathered wood.
- Larvae: Caterpillars feed primarily on lichens and algae; some may also graze on mosses or organic films.
- Pupae: Pupation often occurs in protected crevices (bark cracks, leaf litter, under loose bark) in a light silk cocoon.
- Adults: Adults emerge to mate and disperse; many are active at night and frequently come to porch lights.
Diet & Feeding Behavior
The defining trait of lichen moths is larval feeding on lichens and algae. Lichens contain unique compounds that can be unpalatable to predators. Some lichen moth species tolerate or store these compounds, which may provide a measure of chemical protection. This is one reason certain lichen moths display brighter colors—bold patterns can function as a warning signal to birds and other predators.
Habitat & Where They’re Found
Lichen moths occur across North America and around the world, with many species tied to habitats where lichens thrive. Common locations include forests and woodlands, older neighborhoods with mature trees, rocky outcrops, shaded fences, and structures where algae and lichens develop over time. Because lichens are sensitive to air quality, lichen moth abundance is often higher in cleaner environments.
Behavior
Most lichen moths are nocturnal and are commonly seen at outdoor lights. During the day, adults rest on trunks, rocks, or walls, relying on camouflage. If disturbed, they may fly a short distance and settle again. Mating typically involves pheromone signaling, with females releasing scents that attract males from nearby areas.
Are Lichen Moths Dangerous or a Pest?
In most cases, lichen moths are not structural pests and do not damage gardens, crops, clothing, or stored foods. Their larvae feed on lichens and algae rather than chewing leaves, wood, or fabrics. If you’re seeing adult moths indoors, it’s usually because they were attracted to lights and entered through gaps around doors, windows, or screens—not because they are breeding inside the home.
Prevention & Control
Because lichen moths are typically harmless, control is usually unnecessary. If they become a nuisance around exterior lighting or occasionally wander indoors, focus on exclusion and light management rather than pesticide applications.
- Reduce attraction: Switch bright white bulbs to warmer “amber” style bulbs or use motion lighting to reduce nighttime draw.
- Seal entry points: Repair screens, add door sweeps, and seal gaps around window frames and utility penetrations.
- Remove strays: Indoors, gently capture and release or vacuum and dispose of individuals.
- Limit surface growth near entryways: If algae/lichen buildup near doors and windows is heavy, periodic cleaning can reduce resting sites (aesthetic maintenance, not required for control).
If you suspect moth larvae are damaging fabrics, pantry items, or carpets, you may be dealing with a different moth species entirely. Correct identification is key before taking action.
When to Seek Professional Help
Professional help is rarely needed for lichen moths. Consider contacting a pest control professional only if moth activity is persistent indoors and you need help identifying the species and locating entry points. If you see caterpillars feeding on fabrics or stored foods, it’s likely not a lichen moth, and a targeted inspection may be worthwhile.