This is a Silvery Checkerspot butterfly. This species is larger than the Pearl Crescent and less common. The most noticeable difference (other than size) is that some of the dots in the bottom row are square-shaped and have white centers.

Pearl Crescents have a long flight period; they can fly from late April through early November (weather permitting).

The Pearl Crescent butterfly is one of our area's most abundant species (perhaps second only to the Cabbage White in sheer numbers). Pearl Crescents are found in almost every grassy field, meadow, and lawn. The photo at left shows several Pearl Crescents crowded onto a single Queen Anne's Lace flowerhead. 

Silvery Checkerspots have at least two broods. I see them from late May through mid-June, and also from late-July through August. In 2018, I found one individual on September 16th, an unusually late date for this species. 

This is a female Pearl Crescent. (Females tend to be lighter in color than the males.)