Little yellow butterfly

Small, with elongated forewings. Upperside yellow with black markings, female with more extensive black than male. White form very rare. Underside of forewing with orange or yellow patch at base of wing and black spots at outer wing edge. Winter form has dusty green hindwing, summer form hindwing is pale yellow.
Wing Span: 3/4 - 1 1/4 inches (2 - 3.2 cm).