See remarks under P. comma for longer discussion. This species is very similar to P. comma, and where the two are found together they are easily confused. Generally P. satyrus is a little lighter and more yellowish above (never has a dark summer form), with the submarginal pale spots larger and less well-defined. On the under side the comma mark on this species averages a little larger, and the edge where the dark and light areas meet through the middle of the hind wing is straighter. P. comma only occurs with this species along it's southern limit eastward from the Rockies.
Plain patterned females are most difficult to tell apart (they occur in all species), because the pattern below is not always obvious and has little contrast (but it is still there); plus, the comma mark may not be fully developed. "Plain" females can usually be identified by comparing the arrangement of the faint pattern below with "normal" individuals; and, the upper side remains unchanged.
P. faunus is found in most of the same areas where P. satyrus occurs, but is even more strongly associated with cool wooded habitats. It often has slightly more irregular wing margins, and the dark areas above are often thicker and usually of a much darker hue. Below the pattern is more irregular and broken or "bark-like" or sometimes almost checkered in appearance, and there is often much more prominent green coloring near the margins (often lacking in plain patterned females though). The comma mark on P. faunus is more likely to be hooked on only one end, and it is smaller.
Some comparisons of undersides with P. satyrus two on left; P. comma two in middle; and P. faunus two on right:
And upper side - P. satyrus left; P. comma [winter form] middle; P. faunus right:
Other species that occur with P. satyrus may be very similar above, but are never of the same rich brownish hues below (mostly dull grays to blackish or dark grayish brown, instead of warm yellowish brown). The pattern below on those is made up of finer linear striations, and the comma mark is small, "L"-shaped, and tapered to both unhooked ends.
Much of Canada and United States south of the Arctic and west and north of the Great Plains. Southward mostly limited to mountain areas, and barely into mountains of northern Mexico. East across southeastern Canada and northeastern US to the Atlantic. The distribution is roughly complimentary to closely related and more southeastern P. comma.
Primarily associated with edges of wooded areas where host plants can also be found.
Larval hosts are primarily in the family Urticaceae, with Nettles (Urtica) and Hops Humulus the primary genera utilized. Reports of other genera such as Willows Salix or Ribes seem unlikely, may be based on misidentifications of larvae, and need substantiation. Ulmus may be used occasionally?
Adults only occasionally take nectar from flowers, prefer tree sap, and will also drink from moist ground, fruit, animal excrement, etc.
In most areas probably only one brood occurs, with adults long-lived, maturing in summer/early autumn, and overwintering. Eggs are laid in spring and hatch soon after, with larvae maturing rapidly and the pupal stage brief. In some areas where summers are long, there may be two broods, but this needs substantiated. Adults can be found year-round, but are least common in late spring and early summer.
Occasional specimens are found which may be hybrids between this species and P. comma, but the two seem to remain distinct where their ranges overlap.