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State Insect of Maryland Lesson: The Baltimore Checkerspot Butterfly

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Maryland's state insect is the Baltimore checkerspot butterfly. It was designated in 1973, one of the earliest insects to be honored as a state emblem. It was chosen in part due to its bright orange and black colors, which are the same as the colors of the Calvert family, Maryland's founders.

The Baltimore Checkerspot Butterfly's Scientific Name

Maryland's state insect belongs to a group of butterflies that are distributed around the world, from chilly northern regions to steamy tropical zones. The scientific name for this group is the family Nymphalidae. It There are many kinds of butterflies in the group, and they all share some special characteristics.

The scientific name of the Baltimore Checkerspot Butterfly is Euphydryas phaeton. That means the genus name is Euphydryas and the species name is phaeton. Scientific names have the genus name first and the species name second. This is something like having your last name first – it shows you belong to a closely related group, but within that group are individual species. The Baltimore checkerspot's species name is phaeton. Therefore the insect's scientific name is Euphydryas phaeton. Scientific names are always in italics.

As a middle school teacher myself, I wrote this guide to be useful for both students and teachers. It's a great place to start for research ideas and science fair projects!


Checkerspot Butterfly Identification

Checkerspot butterflies are much more common in the American West and Southwest than in the East – in fact, the Baltimore checkerspot is the only representative of its genus east of the Rocky mountains. In many years of stalking butterflies in all environments, I have yet to encounter a Baltimore checkerspot, a reflection of their rarity. These insects live in colonies and they seldom stray very far from these populations, so unless you stumble upon a field that hosts a colony, you are unlikely to find this species.

This is a very pretty little butterfly, as are all of the Euphydryas checkerspots. The ground color is a deep chocolate brown. Around the margins of the upper wings is a double row of bright orange and yellow spots or lunules. Underneath, the "checker" effect is beautifully enunciated with a complex pattern of orange, yellow and brown. The males and females are similar in appearance.

Caterpillar of the Baltimore Checkerspot

Caterpillar of the Baltimore Checkerspot

Baltimore Checkerspot Early Stages and Caterpillar

After mating, the female checkerspot butterfly lays her fertilized eggs on leaves of the caterpillar foodplant, turtlehead, false foxglove, plaintain, and ash. As they eat and grow, the caterpillars construct silk "nests" where they shelter from predators like wasps, birds, and spiders.

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Over the course of a few weeks, the tiny checkerspot caterpillars eat and grow. Since they have an exoskeleton, a cuticle-like body covering, they have to shed their skin in order to get larger. With each shedding of the skin, called "instars," the caterpillar gets larger. Finally the mature caterpillar sheds its skin and becomes a pupa; the adult butterfly hatches out in the spring and the process repeats.

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Complete Metamorphosis

"Complete metamorphosis" is the term used to describe the life cycle of insects that go through a four-stage sequence of forms. For butterflies, this means egg-larva-cocoon/chrysalis-adult. It helps to take the butterfly as the example, although dragonflies, bees, wasps, flies, beetles, and many other insects also go through complete metamorphosis. Like butterflies, they all have larvae and all of the other developmental stages.

The Baltimore checkerspot butterfly is typical of the insects that undergo complete metamorphosis. The eggs are laid on leaves of the foodplant, and the caterpillar that hatches out eats the leaves of the plant. As it grows, it sheds its skin, also known as molting. The stages between molts are called instars, and after the last instar, the caterpillar sheds its skin one more time.


The last tine the caterpillar sheds its skin, it enters the cocoon/chrysalis phase, known by scientists as "diapause." It's also called a "pupa." Inside the pupa, the insect's cells are rearranging. They actually break down into a kind of goop, and then reassemble to form the body and wings of the adult butterfly or moth.

The final "instar" occurs when the insect hatches out of the pupal skin. It is now ready to mate and continue the cycle. The adult feeds just enough to promote the goal of mating and laying eggs; other than that, it has no purpose on this planet.

The "Spanish fritillary," a European relative of the Baltimore checkerspot

The "Spanish fritillary," a European relative of the Baltimore checkerspot

Butterfly Conservation and Protection

Although the Baltimore checkerspot is considered relatively rare, it is not critically endangered at this point. The butterfly has a wide, if scattered, range across the eastern United States. However, butterflies of all kinds are completely reliant on having the right food plants and environment if they are to survive. When humans tear up fields and forests to build subdivisions and industrial parks, it's the butterfly's home that gets destroyed. We need to be thoughtful and careful, or butterflies like the Baltimore checkerspot could easily become endangered.


The following sources were used for this guide:

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

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