Moths in Pennsylvania

If you run a porch light in Pennsylvania, the moths you see shift sharply through the year. In April and May the most-recorded species in our open-data set are the Eastern tent caterpillar moth (Malacosoma americana), the spongy moth (Lymantria dispar), and the pale beauty (Campaea perlata), with the first Luna Moths (Actias luna) showing up at lights. By July the lineup turns spectacular: the Imperial Moth (Eacles imperialis), the Rosy Maple Moth (Dryocampa rubicunda), the Io Moth (Automeris io) in June, and day-flying hawkmoths like the Hummingbird Clearwing (Hemaris thysbe) and Snowberry Clearwing (Hemaris diffinis). Come August and September, tussock and tiger moths dominate the records, including the Banded Tussock (Halysidota tessellaris), Hickory Tussock (Lophocampa caryae), and Virginian Tiger Moth (Spilosoma virginica). And in the cold months, hardy overwintering species turn up: the fall cankerworm (Alsophila pometaria), Bruce spanworm (Operophtera bruceata), and the famous Isabella tiger moth (Pyrrharctia isabella), whose larva is the woolly bear. This page is built from the moths most often recorded in open GBIF data across Pennsylvania, so it leans toward common, well-photographed species rather than a complete checklist.

Which moths show up first in spring?

Pennsylvania's spring (roughly April into May) is the warm-up act. The most-recorded species in our April data are the Eastern tent caterpillar moth (Malacosoma americana) and a run of geometrid "loopers" like the gray spring moth (Lomographa glomeraria), the tulip-tree beauty (Epimecis hortaria), and the curve-toothed geometer (Eutrapela clemataria). The grapevine epimenis (Psychomorpha epimenis), a small day-flying noctuid, is a classic early-season sighting. April is also when the first Luna Moth (Actias luna) records appear, and the spongy moth (Lymantria dispar) is already on the wing.

By May, the tent caterpillar moth and spongy moth are still near the top, joined by the pale beauty (Campaea perlata), the bristly cutworm (Lacinipolia renigera), and the forest tent caterpillar moth (Malacosoma disstria). If you are hoping for a Luna, May is one of your better windows in much of the state.

What's flying at the peak of summer?

This is the season most Pennsylvania moth-watchers wait for. June brings the Io Moth (Automeris io) into the most-recorded set, alongside the large lace-border (Scopula limboundata), the Hickory Tussock Moth (Lophocampa caryae), and a scattering of crambid grass moths like Microcrambus elegans.

July is the silkmoth and hawkmoth high point in the data. The Imperial Moth (Eacles imperialis) and the Rosy Maple Moth (Dryocampa rubicunda) both rank among the top July records, and the day-flying Hummingbird Clearwing (Hemaris thysbe) and Snowberry Clearwing (Hemaris diffinis) appear as well. You will also see the Clymene moth (Haploa clymene) with its bold "cross" pattern, the painted lichen moth (Hypoprepia fucosa), and the Ailanthus Webworm Moth (Atteva punctella), an orange-and-white species that is hard to mistake for anything else.

Why does late summer look so different?

August and September in Pennsylvania are dominated by tussock and tiger moths rather than the big silkmoths. The Banded Tussock Moth (Halysidota tessellaris) tops the August records, followed by the Hickory Tussock Moth (Lophocampa caryae), the milkweed tussock (Euchaetes egle), the dogbane tiger moth (Cycnia tenera), and the fall webworm (Hyphantria cunea). The Virginian Tiger Moth (Spilosoma virginica) and yellow-collared scape moth (Cisseps fulvicollis) climb the list too.

September keeps that tussock-and-tiger character but adds autumn noctuids: the bronzed cutworm (Nephelodes minians), Smith's dart (Xestia smithii), and Herald-like fall species, with the woolly bear's parent, the Isabella tiger moth (Pyrrharctia isabella), a steady presence.

What about the cold months?

Pennsylvania genuinely has winter moths. From November through February the most-recorded species include the fall cankerworm (Alsophila pometaria), the Bruce spanworm (Operophtera bruceata), and overwintering noctuids like Eupsilia morrisoni and the green cankerworm relatives. Even in deep winter you will see records of the Giant Leopard Moth (Hypercompe scribonia) and the bagworm (Thyridopteryx ephemeraeformis) cases hanging on twigs. February and March is also when the big Cecropia Moth (Hyalophora cecropia), Pennsylvania's largest native moth, starts to appear in the data, along with early Promethea silkmoth (Callosamia promethea) records and the first Orthosia hibisci of the season.

Charismatic species to watch for in Pennsylvania

If you want the showstoppers, the giant silkmoths (family Saturniidae) are the ones to target, and several are in our Pennsylvania data: Luna (Actias luna), Cecropia (Hyalophora cecropia), Polyphemus (Antheraea polyphemus), Promethea (Callosamia promethea), Io (Automeris io), and Imperial (Eacles imperialis), plus the smaller but unmistakable Rosy Maple Moth (Dryocampa rubicunda). For hawkmoth fans, the bumblebee-mimicking Hemaris clearwings fly by day around flowers in summer.

A note on what this list is and is not: these are the moths most often recorded in open-licensed GBIF records (CC0 and CC-BY) across an approximate Pennsylvania area, with butterflies excluded. That means the list skews toward common, easy-to-photograph, and frequently reported species. It is a "most likely / most recorded" picture, not an exhaustive checklist of every moth in the state, and Pennsylvania almost certainly hosts far more species than appear here.

How do I get tonight's personalized list?

Enter your location and Tonight's Moths builds a list tuned to your spot and the current date, drawing on the same kind of monthly GBIF data shown above. It also calculates a "good mothing night" score from the local weather and moon, since warm, calm, humid nights with little moonlight tend to bring the most moths to a light. We are a forecast and discovery tool, not an identifier: once you have photos, iNaturalist and the Moth Photographers Group / BAMONA (Leps) are great for confirming an ID.