Baltimore checkerspots can be identified at a glance. The upper side of this medium-sized butterfly is black at the bases of the wings, with several rows of white spots in the middle of the wings, and a band of orange spots along the wing margins. Viewed from below, the wings have a black and white checkered pattern with basal orange spots and orange spot bands at the margins. The Baltimore checkerspots that live in our region tend to be darker than ones to the north and east of our state.
Caterpillars are black with orange stripes and bands, and rows of branching black spines.
Similar species: There’s really no mistaking a Baltimore checkerspot. Other Missouri butterflies that look rather checkered include the gorgone checkerspot, silvery checkerspot, pearl crescent and other crescents, and fritillaries — but these look very different.
Wingspan: 1¾–3 inches.
Mostly in the Ozarks; rare in other parts of the state. We represent a southwestern edge of their total territory; most of their North American range is north and east of Missouri.
Habitat and Conservation
Populations fluctuate greatly from year to year. In Missouri, this species is most frequently observed on dry hills and ridges in Ozark woodlands. Elsewhere, they prefer damp grassy areas. In some areas of its overall range, it may be declining. If you are wanting to find a colony, go to the Ozarks, find its principal Missouri food plants (gerardias or false foxgloves), and look for eggs or larvae.
In many places, Baltimore checkerspots reportedly lay their eggs on turtlehead plants (Chelone spp.). Apparently, Missouri populations prefer gerardias and false foxgloves (formerly in genus Gerardia). Taxonomists have reclassified and named these plants. Missouri species include combleaf yellow false foxglove (Aureolaria pedicularia, also called A. pectinata), slender gerardia/false foxglove (Agalinis tenuifolia), rough-stemmed gerardia (Agalinis gattingeri), and several more. Baltimore checkerspot larvae are also reported on English plantain (Plantago lanceolata) and some species of Pedicularis (wood bettony/lousewort) and penstemons.
Adults visit flowers, carrion, and animal droppings, and they also frequently visit mud puddles and moist spots on the ground.
Breeding resident; rare in western Missouri but locally abundant in the eastern Ozarks.
There is a single brood, with adults flying from late May into early July. Males select low perches to wait for females. On the undersides of host plant leaves, females lay two or three clusters averaging 275 eggs. The caterpillars live together in a silken nest on the food plant their first summer. This nest consists of webbing that starts by covering the top of the plant and keeps extending downward until late summer, when they construct a thicker, smaller web. They remain inactive in the web until the group moves to the ground in the fall. The pre-hibernation web provides a refuge until cool weather reduces the numbers of predatory insects, spiders, and so on. The webs are not sturdy enough for overwintering. At that point, they gradually break into smaller groups that will overwinter as partially grown larvae in rolled, silked-together leaves. The following spring, the caterpillars disperse and feed on a wide range of shrubs and nonwoody plants.
In 1973, the Baltimore checkerspot was declared the official state insect of Maryland. Some say it was named because its checkered black and orange pattern reminded people of the pattern on the coat of arms used by George Calvert, the English First Baron of Baltimore who was a principal colonizer of Maryland in the 1600s. Indeed, Maryland’s state flag includes the black-and-yellow checkered pattern of Calvert’s heraldry.
The Baltimore oriole, a black and orange bird, received its name for basically the same reason. And yes, it is Maryland’s official state bird.
The bright orange and black pattern apparently serves as a warning to predators that this species is unpalatable or toxic. Depending on the food plant, they may indeed accumulate bad-tasting chemicals in their bodies, much like monarchs and viceroys do.