The Baltimore checkerspot butterfly, also known as Euphydryas phaeton, is a common North American butterfly known for being the state insect of Maryland since 1973.
Baltimore Checkerspot Species Summary
| Scientific Name | Euphydryas phaeton |
| Family Name | Nymphalidae |
| Kingdom | Animalia |
| Genus | Euphydryas |
| Habitat | Wet meadows, bogs, marshes, dry open or wooded hillsides |
| Range | Texas, Nebraska, Georgia, Mississippi, Oklahoma, Nova Scotia |
| Host Plants | Turtleheads, English plantain, false foxglove |
| Butterfly Description | Black wings with red/orange patterns on the outer margin |
| Caterpillar Description | Black head with alternating orange and black bands |
Reproduction, Lifecycle, and Timespan
The Baltimore checkerspot lifecycle starts in early summer when males and females begin the mating season. The egg stage lasts for about 20 days. Caterpillars will climb the tip of the plant and feed together in a web. They will then overwinter in dead leaves until mid-April when they resume feeding. The chrysalis stage lasts for about 2 weeks.
Butterfly Description and Identification
The Baltimore checkerspot (Euphydryas phaeton) belongs to the family Nymphalidae (the brush-footed butterflies), genus Euphydryas.
The upper side of this butterfly’s wings is black, with red/orange patterns on the outer margin of both wings. It also has several rows of white spots going inward. Orange dots are present closer to the butterfly’s body, making it similar to the Bay checkerspot. The wingspan ranges from 1 3/4 to 2 3/4 inches (4.5 to 7 cm).
Caterpillar Appearance
The Baltimore checkerspot caterpillar has a black head with alternating orange and black bands. Its spikes are located on top of the black bands. From a distance, the coloration of the caterpillar is similar to that of an adult butterfly.
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Baltimore Checkerspot Chrysalis Description
Baltimore checkerspot chrysalis is white, with orange, yellow, and black markings. It’s a unique chrysalis, and you’ll easily spot it if you know what you’re looking at.
Baltimore Checkerspot Butterfly Range
Besides isolated sightings in northern areas of Texas and Nebraska, this butterfly is present in:
- Nova Scotia
- Great Lakes region
- southeast Manitoba
- northern Georgia
- northern Mississippi
- northeast Oklahoma
What Is the Baltimore Checkerspot Butterfly’s Main Habitat?
This butterfly prefers:
- Wet meadows
- Bogs
- Marshes
- Dry open or wooded hillsides
Are Baltimore Checkerspot Butterflies Endangered?
Due to the current drop in numbers, the Maryland Department of Natural Resources lists Baltimore checkerspots as rare, threatened, and endangered. Habitat loss and degradation, climate change, and habitat fragmentation are the main threats to this species.
However, it still inhabits wetlands of the western and central regions — wild colonies are present around 20 cities in 8 counties, and the Blue Ridge, the Appalachian Plateau, and Piedmont.
How Can We Help Baltimore Checkerspot Butterflies?
There have been several attempts to restore the species. Experts focus on maintaining and monitoring current colonies, finding wetlands to support new territories, and managing captive breeding programs.
Individuals can report any sighting to help update the numbers and ranges. Planting turtlehead may become a common practice in the future, as it can help establish the species on a broader range.
Baltimore Checkerspot Host Plants
Females lay eggs on the following plants:
- Turtlehead (Chelone glabra)
- English plantain (Plantago lanceolata)
- False foxglove (Aureolaria)
- White turtlehead
- Hairy beardtongue (Penstemon hirsutus)
What Do Baltimore Checkerspot Butterflies Eat?
The caterpillar will eat the host plants before hibernation. After overwintering, it may still munch on those or go on to feed on other plants, such as:
- Arrowwood (Viburnum recognitum)
- Japanese honeysuckle (Lonicera japonica)
- White ash (Fraxinus americana)
- Common lousewort (Pedicularis canadensis)
Adult checkerspots feed on nectar from milkweed, dogbane, viburnum, wild blackberry, and wild rose, as these bloom during their flight period.
Butterfly Behavior
Baltimore checkerspot’s flight is fast and erratic. When not flying, males perch near the ground to find females. This usually happens in the early summer. After mating, females will lay eggs in groups of 100 to 700 below the host plant leaves.
Eggs will be yellow at first, then change to red in about 20 days. Hatched caterpillars will move to the tip of the plant and form a web to feed. The fourth instar of the larvae hibernates in leaf rolls on the ground. Caterpillars will eat, grow, and molt during the summer.
This species has one brood flying from May to June in the south and one flying from June to August in the north.
Most Common Caterpillar Issues and Predators
Baltimore checkerspot caterpillars suffer high mortality from falling off the leaves of host plants. Besides the falls, caterpillars will often become victims of Braconid wasps. To deal with the predators, young caterpillars will build a web to keep them protected while they eat.
Are Adult Butterflies Poisonous?
Birds, insects, spiders, and small mammals attack adult butterflies. Luckily, the adults are poisonous to birds, and have bad taste. They’ll warn their predators by spreading their colorful wings while drinking nectar from flowers.
4 Interesting Baltimore Checkerspot Butterfly Facts
- It’s a North American butterfly and the official state insect of Maryland since 1973.
- This butterfly was named after George Calvert, the first Lord Baltimore, as its colors matched George’s heraldic shield.
- Baltimore checkerspot belongs to the family Nymphalidae, and appears as if it has 4 legs instead of 6.
- This species rarely visits gardens.
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