This, and the next photo, were taken on the other side of Lolo Pass along the Wild and Scenic Lochsa River. So while not technically in Montana, very close. This was just one of many California Tortoiseshells observed. Kristi saw clouds of these along the river.
The brightly colored dorsal (upper) side of the wings is opposite to their ventral (under) side, which looks more like a dead leaf. These amazing butterflies are among the first butterflies we see in the late winter / early spring (as early as March). The new generation emerges in late July and August here in Montana. They do a short “summer hibernation” soon after emerging and become active again in the late summer and fall. They will then head into their winter hibernation and begin flying once the weather warms up in March or April. This individual butterfly can therefore have a lifespan of 9 to 10 months.
Size: 32-70 mm
Photo by: Kristi DuBois on 8/29/21 in Idaho County, ID