Similar to the Question Mark, but smaller, and usually less common. Occurs in similar habitats. "Comma" mark on lower hind wing is large, often a little curved, and hooked at least on one end (usually both); only very rarely is it divided (if so, usually on "plain" females). On some other species the mark is "L"-shaped and not hooked, and on Question Mark it is usually devided into a large and small portion to make the "question mark" it is named for. On upper forewing of Question Mark, there is a row of four dark "postmedian" spots, but only three in the Comma and other Polygonia species. Ragged edge of hindwing is distinctive compared to Question Mark, where hindwing is fairly straight. Both species have winter and summer forms, with the lighter form overwintering and seen flying mostly in autumn and spring and the darker form mostly seen in summer (some individuals fly at the wrong time or are intermediate in coloring though).
The Satyr (P. satyrus) is very similar, but the color above is usually more yellowish with larger less well-defined light submarginal spots. It has no dark summer form. Below the comma mark is usually larger and the markings are less irregular with the zones of coloring more straight-edged. It is mostly found further north and west, but the two species overlap and can fly together in some areas.
The Faun or Green Comma (P. faunus) tends to be found in higher elevations, further north, and further west, but is confusingly similar when the two are together. Even though it has no dark summer form, it usually has the outer parts of the wings mostly rather dark in color, but with contasting lighter spots. It has the wing margin more irregular and the pattern more broken and irregular-looking (especially below). Usually (except in some plain females) there is much more and more distinct green to bluish coloring near the margin of the underside. The overall impression below is of a somewhat "checkered" pattern with lots of green near the margin. In the Question Mark, Comma and Satyr the underside pattern looks more banded, usually in warm shades of brownish, with the green present but not very noticeable.
The remaining species all have the comma mark below smaller and "L"-shaped, with the underside pattern more blackish or gray, and looking striated with narrow parallel lines.
Of these, only the Gray Comma - P. progne has about the same distribution and has a dark summer form. It has smaller pale dots on the hind wing that almost always show up well even in the dark form, and usually has smaller black spots on the front wing. The hind wing usually has less dark pattern in the basal half. However, they can be very hard to tell apart if just seen from above.
The other "gray" species mostly have larger less well-defined submarginal pale spots above, and are more likely to be confused with P. satyrus (and mostly occur further north or west).
Comma (left); Question Mark (middle); Gray Comma (right):
Deciduous woodlands and edges, usually near water.
Typically October/November and March-April (fall form, overwinters), May-September (summer form). Fall form may emerge on warm winter days.
Larvae feed primarily on Hops (Humulus) and Nettles (Urtica, but also False Nettle (Boehmeria), Wood Nettle (Laportea), Elm (Ulmus), and probably other members of families Urticaceae and Ulmaceae.
Adults take fluids from damp sand, rotting fruit, sap (especially), but only rarely nectar from flowers.
Two broods. Overwinters as adults, mostly of lighter color form.