Fritillaries are a Brush-Footed butterfly, they have the six legs, but the two front legs are very small and covered with bristles, which makes them appear to only have four legs. There are many varieties of Fritillary butterflies. Here are two Great Spangled Fritillaries I saw while in northern Minnesota.
Great Spangled Fritillaries are common and conspicuous, found in the northern and central U.S. and southern Canada. They are seen in meadow and field areas. These fritillary are large with prominent silver spots on underside of hindwing. They feed milkweeds and thistle. The caterpillars eat the leaves of violets.