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Baltimore Checkerspot

Scientific Name

(Euphydryas phaeton)

The Baltimore checkerspot is a medium-sized butterfly in the family Nymphalidae. This species ranges from Canada southward to the mountains of Virginia and North Carolina and westward to the Great Lakes. Historically, this species was distributed in 15 counties of Maryland and was relatively common. Today, however, colonies are only known from 11 sites in 7 counties of western and central Maryland (1).

Life Cycle

Baltimore checkerspot butterflies have one generation per year, with a Maryland flight period varying from June into early July. After mating, female butterflies can lay several hundred eggs on the larval host plant, white turtlehead. Eggs develop for 20 days and then hatch into tiny caterpillars that begin feeding. They build a communal web where they often gain protection from predators and parasitic wasps.

During the summer caterpillars eat and grow, molting into second and third instar larvae. Mid-August they stop feeding and molt one more time into the fourth instar larvae. They then enter a state of diapause at the end of October, where they stop feeding. When temperatures get cooler, they move out of the web and into the leaf litter, where they roll up in leaves and debris to prepare for winter (1, 4).

Habitat

Open wet meadows with few trees and shrubs. Common nectar sources for adults include milkweeds, dogbane, several species of mountain mint and wild blackberry (1).

Baltimore checkerspot caterpillars feed almost exclusively on white turtlehead (Chelone glabra L.), especially during early development (1). When they are much larger, caterpillars may use a variety of other host plants, including arrowwood viburnum (Viburnum recognitum Fernald), narrow-leaved plantain (Plantago lanceolata L.) [not native], penstemon (Penstemon spp. Schmidel) and honeysuckle (Lonicera spp. L.) (1).