A colony of Canada thistle (Cirsium arvense) along the Tule River (Shasta County CA) recently was filled with a variety of butterflies including west coast painted ladies (Vanessa annabella), Milbert’s tortoise shells (Aglais milberti), various sulfurs and red admirals (Vanessa atalanta).
Red admirals are found worldwide in the temperate regions of the Northern Hemisphere and are widespread in North America, preferring open areas.
A colorful butterfly, the forewings of a red admiral are black with a red-orange medial band (in the middle of the wing) and white subapical spots (in from the front outer edge). The black hindwings have a red-orange submarginal band and small black submarginal spots. (Submarginal = in from the edge of the outer margin) The ventral (under) side of the wings are a mottled grey-brown with darker spots.
Red admiral caterpillars (larvae) live and feed singly on nettles in the spring, drawing the edges of the leaf together and holding the folded leaf in place with silk. Red admirals belong to the group of butterflies know as “thistle butterflies” because the adults frequent flowers, particularly thistles. Adult red admirals fly during the day.
Red admirals are double brooded butterflies. The second brood of the year results in butterflies that are larger and darker than the first brood. Adults hibernate overwinter.
All the butterflies flitting among the Canada thistles resembled a cloud of colorful confetti atop the flowers.