How to identify the Salt Marsh Moth
The Salt Marsh Moth is a medium to large tiger moth with a wingspan of roughly 4.5 to 6.8 cm (about 1.8 to 2.7 inches). The forewings are chalky white, scattered with a loose pattern of small black spots; females tend to be cleaner white while males often show a yellow or buff wash on the hindwings. The giveaway is the abdomen: it is yellow-orange along the top with a row of black dots down each side. At rest the moth holds its wings in a low tent shape over the body, and the fuzzy white thorax adds to its woolly look.
Where the Salt Marsh Moth lives
Despite the name, this moth is not limited to coastal marshes. It is one of the most widespread moths on the continent, and the open GBIF records show it concentrated in Texas, California, Florida, New York and Virginia. It does well in open, disturbed and agricultural habitats: fields, gardens, roadsides, weedy lots and yes, salt marshes. Because it tolerates so many habitats, it is a moth many people in the US and Canada can find close to home.
When the Salt Marsh Moth flies
This species is multi-brooded, so it appears across a long stretch of the warm season. In the records it peaks in April, May and again in September, reflecting a spring generation and a later-season generation. In the warmest parts of its range it can be on the wing across much of the year, while in the north the spring and early-fall windows are your best bets.
Caterpillar, host plants and life cycle
The larva is the familiar "salt marsh caterpillar," a fast-moving, very hairy caterpillar that ranges from pale yellow to dark brown or nearly black, with tufts of long hairs. It is a broad generalist feeder, eating many low plants including clover, cotton, cabbage, dandelion, plantain and various weeds, which is why it sometimes turns up as a minor garden or crop nibbler. Like many tiger moth caterpillars its hairs can irritate sensitive skin, so it is best not to handle it. The species overwinters as a pupa in a loose cocoon spun with the caterpillar's own hairs, then emerges as an adult to start the next generation.
How to see a Salt Marsh Moth at night
Salt Marsh Moths come well to artificial light, so a simple light setup on a warm spring or early-fall night is the easiest way to meet one. Hang a white sheet and shine a UV (blacklight) or mercury-vapor lamp on it; short-wavelength UV pulls in far more moths than a plain white LED porch bulb. Moths gather at lights because bright artificial light disrupts their flight orientation, not because the light "attracts" them as a goal, so a steady light against a pale backdrop works best. Check your sheet through the first few hours after dark. For more tips, see our good night for moths guide.