Can you ID this large brown moth?


Hoping your experts there can help identify this very large brown moth that was in my house.

My photo is not very good. The moth was about five inches across.

We were able to trap it in our window, removed the screen, and it flew away.

Thank you.

Lisa, Ventura County - August 26, 2021

Curator Response

Dear Lisa,

This is the Black Witch Moth, Ascalapha odorata (family Noctuidae), one of California’s largest moths. Males and females are easily distinguished—the one in the photo is a female based on the bold whitish stripe that runs across both the front and hind wings on each side (males are darker and lack the bold stripe). This species is notable not only because of its size, at 5-7 inches across, but also because it has a strange "emigration" pattern. Each year during warm and humid weather, waves of individuals spread northwards from the usual breeding grounds in Mexico, usually passing through the Central Coast by August. By about October, some individuals (predominantly males) have even made it up to the middle of Canada. The interesting part is that they don’t seem to either persist in or fly back south from these locations; however, in some places, including mild Southern California, they may lay eggs and complete a generation or two as the caterpillars feed on ornamental acacias, but there are no known established breeding populations in the US. It is still a mystery why so many individuals would bother to fly so far northward, apparently ensuring the pruning of their family trees. In this context, I use the word emigration rather than migration to make the distinction between cyclical travel (migration) and going somewhere and not returning (emigration).

As you might expect with such a large, startling-looking creature that is widespread across the Americas, there are many folkloric legends surrounding it, and it is interesting to note the contrasting views. In Mexico, they are sometimes known as “Mariposa de la muerte,” or “Butterfly of Death,” and there are many morbid legends surrounding its entry into a person’s home, especially if that person is already ill. In parts of the Caribbean, however, it is known as the “Money Moth,” and legend has it that if one visits a person’s home, that person will likely experience a financial windfall!

Stay curious,

Schlinger Chair and Curator of Entomology Matthew L. Gimmel, Ph.D.