Step outside near a porch light on a warm Colorado evening and the sheer variety of moths fluttering in can be startling. Among the many types of moths in Colorado, residents encounter everything from a small gray pantry pest to a sphinx moth so large and fast it gets mistaken for a hummingbird. Some arrive by the millions during a spring migration, while others spend their entire lives tucked inside a single closet.
This guide walks through 16 moths commonly found across the state, from the foothills to the eastern plains, covering what each one looks like, where it turns up, and what it eats. Some are garden visitors worth watching for; others are the reason a wool sweater develops holes by March.
1. Miller Moth
The “miller moth” is not a single species but a nickname Coloradans gave to whichever moth swarms homes and cars each spring. In Colorado, that moth is almost always the adult stage of the army cutworm, Euxoa auxiliaris. Colorado State University Extension notes that in Colorado and much of the Rocky Mountain west, the common ‘miller’ is the adult stage of the army cutworm, Euxoa auxiliaris.
As caterpillars, army cutworms feed on winter wheat and garden plants through the cold months. Army cutworm moths are about 1 inch long and variable in color, usually gray or brown with two characteristic light spots on each wing. Every May and June, huge numbers migrate from the eastern plains toward the mountains, swarming porch lights and open doors along the way.
Pro Tip: Miller moths are harmless and temporary visitors. A light left burning over a bucket of soapy water overnight is often enough to clear a kitchen without chemicals.
2. Indian Meal Moth
Few Colorado households escape an encounter with the Indian meal moth at some point. This small moth, Plodia interpunctella, is the most frequent moth problem found inside pantries statewide. According to Colorado State University’s Agricultural Biology program, the Indian meal moth is the most common species of pestiferous moth in Colorado homes.
Adults measure roughly 3/8 inch long, and they are generally gray with rusty brown or bronze coloration on the far half of the wing, which is a distinguishing feature of this species. The caterpillars, not the adults, do the real damage, chewing through grains, dried fruit, nuts, and pet food, then spinning silk webbing across infested packages. Unlike the migratory miller moth, this one can complete several generations annually in Colorado homes, which is why a small problem can snowball fast if pantry items sit unchecked.
3. White-Lined Sphinx Moth
The white-lined sphinx moth, Hyles lineata, is routinely mistaken for a hummingbird as it hovers at flowers with its long proboscis extended. One University of Colorado researcher described watching the species up close, noting three white-lined sphinx moths attended the small yellow flowers that covered the full periphery of the rabbitbrush; they had wingspans of five inches, so they were easy to spot and follow, according to an account published by the University of Colorado Boulder.
The forewings are olive-brown to gray with a bold white band running lengthwise, crossed by thinner white veins, while the hindwings flash pink when the wings open fully. The species is active both day and night and gathers in large numbers around lights and nectar-rich gardens. Caterpillars feed on a wide range of host plants, including evening primrose, and come in color forms ranging from solid green to bold black-and-yellow striped patterns. Because they hover rather than land while feeding, they draw the same crowd of curious onlookers as the native bees found pollinating Colorado gardens.
4. Pug Moth
Pug moths belong to the genus Eupithecia, one of the largest moth genera in North America, with dozens of similar-looking species recorded across Colorado’s foothills and mountain meadows. These moths are tiny, usually under an inch across, with mottled gray or brown wings held flat against surfaces at rest, making them easy to overlook. Because so many pug species look nearly identical, precise identification often requires close examination under magnification rather than a casual glance, a challenge shared with many small moths cataloged among the broader different types of insects found in temperate climates.
Caterpillars of various pug species feed on flowers and seed heads of a wide range of native plants, often matching the color of the blossom they are consuming for camouflage. Adults fly mostly at night and are drawn readily to porch lights, where their small size and plain coloring often let them pass unnoticed among larger, flashier moths.
5. Isabella Tiger Moth
The Isabella tiger moth, Pyrrharctia isabella, is better known in its caterpillar form: the banded woolly bear. This fuzzy caterpillar, with its reddish-brown middle band flanked by black segments, is a familiar sight crossing Colorado sidewalks and trails in late summer and fall as it searches for a sheltered spot to overwinter.
As an adult, the Isabella tiger moth is far less recognizable, with plain yellow-orange to tan wings dotted sparsely with black spots. Folklore has long claimed the width of the woolly bear’s bands predicts how harsh the coming winter will be.
Important Note: The woolly bear’s winter forecasting reputation is a long-standing piece of folklore rather than a scientifically validated method. Band width actually varies with the caterpillar’s age and local growing conditions during the season, not upcoming weather.
6. Fall Webworm Moth
The fall webworm moth, Hyphantria cunea, is easiest to spot not as an adult but through the silky communal nests its caterpillars spin around the tips of tree branches in late summer. These white tents, often mistaken for tent caterpillar nests, enclose entire colonies of hairy caterpillars as they strip leaves from host trees including cottonwood, ash, and fruit trees common across the Front Range.
Adult moths are mostly white, sometimes with small black spots scattered across the wings, and have a wingspan of around 1 to 1.5 inches. While the webbing can look alarming on ornamental and shade trees, established trees typically tolerate the defoliation without lasting harm. The species ranges across most of the continental United States, including areas covered in this guide to types of moths in Georgia, where it is an equally common late-summer sight.
7. Polyphemus Moth
Among the giant silk moths found in Colorado, the Polyphemus moth, Antheraea polyphemus, stands out for its size and the large, eye-like spots on its hindwings. With a wingspan that can reach nearly 6 inches, it ranks among the biggest moths encountered in the state, rivaled by few others outside its own family.
Adults are reddish-brown to tan with transparent, eyespot-centered patches on each hindwing that flash open when the moth is disturbed, a defense meant to startle predators. Like most giant silk moths, adult Polyphemus moths have no functional mouthparts and live only about a week, focused entirely on mating before dying. Caterpillars feed on a range of deciduous trees, including oak, birch, and maple, a diet shared by related silk moths documented among types of moths in Michigan.
8. Blinded Sphinx
The blinded sphinx, Paonias excaecata, takes its unusual common name from the eyespot on each hindwing, which lacks the dark central pupil-like mark found on related species, giving it a “blind” appearance. Forewings are scalloped and mottled in shades of brown and gray, providing excellent camouflage against tree bark when the moth rests during the day.
This moth favors deciduous woodlands and riparian corridors where its caterpillar host plants, including willow, cherry, and birch, grow along streams and foothill drainages. Adults fly at night during the warmer months and are occasionally drawn to lights, though they are less commonly reported than the more abundant white-lined sphinx.
| Sphinx Moth | Typical Wingspan | Common Host Plants | Active Period |
|---|---|---|---|
| White-Lined Sphinx Moth | 2.5 – 3.5 in | Evening primrose, roses, rabbitbrush | Day and night, spring-fall |
| Blinded Sphinx | 2 – 3.5 in | Willow, cherry, birch | Night, summer |
| Poplar Sphinx Moth | 2.5 – 3.5 in | Cottonwood, willow, poplar | Night, early-mid summer |
| Achemon Sphinx Moth | 3 – 3.5 in | Wild grape, Virginia creeper | Night, summer |
| Nessus Sphinx Moth | 1.5 – 2 in | Grape, Virginia creeper | Day, spring |
9. Rocky Mountain Clearwing
The Rocky Mountain clearwing, generally identified as Hemaris thetis, is a day-flying hawk moth that looks and behaves almost exactly like a small bumblebee or hummingbird as it hovers at flowers in mountain meadows and foothill gardens. Its wings are largely transparent, bordered by a thin band of reddish-brown scales, and its body is covered in dense, fuzzy hair in shades of olive and burgundy.
Unlike most moths covered here, this species relies entirely on daylight activity and nectar feeding rather than nighttime flight, making it one of the easier Colorado moths to observe without a light trap. Its range extends north through the Rocky Mountain states and into similar habitats documented among the types of insects found in Canada.
10. Poplar Sphinx Moth
The poplar sphinx moth, generally referred to in the Rocky Mountain region as Pachysphinx occidentalis, is one of the larger sphinx moths found in Colorado, with a wingspan that can exceed 3.5 inches. Its forewings are mottled gray-brown, while the hindwings reveal a flash of dusty rose or salmon when exposed, a pattern typical of the Pachysphinx group of sphinx moths.
As its name suggests, caterpillars feed heavily on poplar, cottonwood, and willow, trees that line many of Colorado’s rivers and irrigation ditches. Adults are nocturnal and rarely seen outside of brief visits to porch lights during early summer evenings, spending most of their short adult lives resting motionless on tree trunks during the day.
11. Achemon Sphinx Moth
The Achemon sphinx moth, Eumorpha achemon, is named for the pinkish-brown, scalloped pattern across its forewings, paired with hindwings that show a bold pink patch bordered in black. This combination makes it one of the more distinctively marked large moths found in the state.
Its caterpillars feed almost exclusively on wild grape and Virginia creeper vines, which grow along fence lines, riverbanks, and wooded edges throughout eastern Colorado. Like other sphinx moths, the caterpillar carries a prominent horn near its rear end when young, though this horn is often reduced to a small button-like eyespot by the time the caterpillar reaches full size.
12. Underwing Moth
Underwing moths, belonging to the genus Catocala, are known for a dramatic disguise-and-reveal defense. At rest, their forewings fold flat and blend seamlessly into tree bark, but if disturbed, the moth flashes brightly colored hindwings in patterns of orange, red, pink, or yellow banded with black to startle potential predators.
Colorado hosts several Catocala species, most feeding as caterpillars on cottonwood, willow, and oak. Because the forewing camouflage is so effective, most people only notice an underwing moth when it startles off a tree trunk in a flash of hidden color, a trait that makes this genus a favorite among moth enthusiasts tracking regional diversity, including those cataloging types of insects in Ohio, where Catocala diversity is especially well documented.
13. Nessus Sphinx Moth
The Nessus sphinx moth, Amphion floridensis, is a small, fast-flying hawk moth easily recognized by two bright yellow bands crossing its otherwise dark brown abdomen. Unlike many of its larger sphinx relatives, this species often flies during the day, hovering at columbine, phlox, and lilac blossoms much like a tiny hummingbird.
Caterpillars feed on wild grape and Virginia creeper, the same host plants favored by the Achemon sphinx, and the two species are sometimes found sharing the same vine tangles along riparian corridors. Adults emerge earlier in spring than most other sphinx moths in the region, often appearing as soon as nectar sources bloom in April and May.
14. Raspberry Crown Borer
The raspberry crown borer, Pennisetia marginata, looks nothing like a typical moth at rest. Adults mimic yellowjacket wasps, with narrow, mostly clear wings and a black body banded in yellow, a disguise that helps them avoid predators that would otherwise target a soft-bodied moth.
The real damage from this species comes from its larvae, which bore into the base of raspberry and blackberry canes, feeding inside the crown and roots for up to two years before emerging as adults. Home gardeners growing berries in Colorado sometimes notice wilting or dying canes long before ever spotting the wasp-mimicking adult responsible, a pattern of hidden damage shared by many borers covered among types of insects that eat wood.
15. Io Moth
The Io moth, Automeris io, is unmistakable once its hindwings are exposed, each marked with a large black-centered eyespot ringed in yellow and blue that mimics the staring eyes of a much larger animal. Males are bright yellow overall, while females run darker, in shades of reddish-brown to purple-brown.
This species is considered uncommon in Colorado compared to states farther east, with caterpillars feeding on a wide variety of host plants including willow and chokecherry. The spiny green caterpillars deliver a genuinely painful sting if handled, since their bristles contain venom glands, so admiring an Io moth caterpillar from a distance is the safer approach.
Pro Tip: Never handle spiny caterpillars with bare hands in the field. The stinging hairs on Io moth larvae can cause a reaction similar to a bee sting or mild chemical burn.
16. Clothes Moth
Unlike most moths on this list, the clothes moth spends its entire life cycle indoors, tucked into closets, attics, and storage boxes rather than gardens or woodlands. The species most responsible for Colorado’s wool and fabric damage is the webbing clothes moth, Tineola bisselliella, a small, buff-colored moth that avoids light and is rarely seen flying in the open.
According to Colorado State University Extension, most fabric moth problems in Colorado homes trace back to imported woolen goods brought into a closet rather than moths that wandered in from outside. Larvae feed on wool, silk, feathers, and fur, leaving behind irregular holes and silky trails of webbing, and because they shun light, infestations often go unnoticed until visible damage appears on stored clothing.
- Store wool and silk items in sealed, airtight containers rather than open boxes.
- Clean garments thoroughly before long-term storage, since larvae are drawn to food and sweat residue, not just fabric.
- Freeze small infested items for several days to kill eggs and larvae without chemicals.
- Use cedar or lavender sachets as a mild deterrent, though they work best alongside proper cleaning and storage rather than as a standalone fix.
From the mass spring migration of the miller moth to the quiet, closet-bound life cycle of the clothes moth, the types of moths in Colorado span an enormous range of size, behavior, and habitat. Anyone curious to compare notes can look at how these species stack up against the types of butterflies found in Colorado, or explore how many types of moths exist worldwide to see just how much diversity this insect order holds beyond the state’s borders.