How to identify the Black Witch Moth
This is a giant, bat-like moth. With a wingspan that can approach 6 to 7 inches, it dwarfs almost every other moth you will meet in the US and is often mistaken for a bat in flight at dusk. The wings are mottled dark brown with iridescent purplish and pinkish highlights. Each forewing carries a distinctive comma or apostrophe-shaped spot, and a pale, jagged band sweeps across both wings. Females tend to be larger and show a stronger pale band than the darker males. Its sheer size and color make it hard to confuse with anything else.
Where it lives
The Black Witch is a tropical species that breeds from Mexico and Central America through the southern US borderlands. Each year individuals wander far north, and in open GBIF records the US strays cluster in Texas, Florida, Arizona, Colorado, and New Mexico, with vagrants turning up much farther north on warm-season winds. It is a stray and dispersal specialist rather than a true resident across most of that range, so any sighting can feel like a lucky event.
When it flies
Most US sightings fall in late summer, roughly June through September, peaking as northbound migrants ride southerly weather systems and are sometimes pushed along by tropical storms. By day, the moth often tucks into shade under eaves, porches, carports, and bridges, then flies at dusk and into the night.
Caterpillar and host plants
The larva is a large, smooth, grayish caterpillar that feeds on legume trees, especially acacia and related woody legumes such as Senna and Cassia, in the warmer parts of its range. Because the Black Witch mainly breeds in the tropics and subtropics, most northern sightings are wandering adults rather than locally raised ones. The caterpillar, like the adult, is harmless.
How to see one at night
First, check sheltered daytime roosts: garage ceilings, porch corners, barns, and the undersides of bridges, especially after a warm front or tropical system from the south. At night, the Black Witch will sometimes come to bright lights, though it is not as reliable at a sheet as smaller moths. A UV or mercury-vapor lamp on a warm, humid night gives you the best odds, since short-wavelength light disrupts moth flight orientation far more than white LEDs. Watch the surrounding walls and not just the sheet, because this big moth often settles nearby rather than landing on the light. If you found a huge dark moth and want to be sure of the ID, our guide on what moth is this walks you through the clues, and you can see which species are likely near you tonight.
Remember, this site does not identify a moth from your photo. It predicts which species are likely at your location and date from open records. For photo ID, try iNaturalist or Seek, BugGuide, the Moth Photographers Group, or BAMONA.