It was a very butterfly-filled weekend for me. I attended the Thornton Burgess Nature Club’s monthly adult natural history program on Saturday. This month’s topic was “Butterflies” with an up close and personal look at a variety of species within the Cape Cod Museum of Natural History’s Butterfly House. Within the Butterfly House, I was able to closely observe monarchs (Danaus plexippus), red admirals (Vanessa atalanta), and question marks (Polygonia interrogationis). 

A newly emerged monarch butterfly.

A question mark butterfly. 

Then today I got to test out my new butterfly net at Crane Wildlife Management Area. I was able to capture and identify eight different species of butterflies, ranging in size from large spicebush swallowtails (Papilio troilus) to small eastern tailed blues (Everes comyntas). But my favorite was the Baltimore checkerspot (Euphydryas phaeton). A striking butterfly, with a wingspan of approximately 2 inches, Baltimore checkerspots have several rows of white spots on the outer halves of both wings against a black background, as well as an outer margin of red-orange crescents. They also have bright orange-tipped antennae and a hairy orange face. 

Although previously considered a relatively local species occurring in small numbers, in southeastern Massachusetts Baltimore checkerspots are becoming a common meadow species, occasionally found in colonies of 1,000 or more individuals. This population increase is likely due to the expansion of the larvae’s preferred food species, including Turtlehead (Chelone glabra), White Ash (Fraxinus americana), Arrowwood (Viburnum recognitum), English Plantain (Plantago lanceolata), and Common Plantain (P. major). English plantain, in particular, although non-native, has been spreading considerably and facilitating the increase in Baltimore checkerspot numbers. The adults prefer different food plants, with orange milkweed (Asclepias tuberosa) and black eyed Susans (Rudbeckia hirta) being among the adults’ preferred food sources. That these were blooming in abundance at Crane likely helped attract the numerous Baltimore checkspots I saw today. 

Baltimore checkerspot feeding on orange milkweed (aka butterfly weed). 

Unlike most butterflies, which overwinter as eggs, pupae, or sometimes adults, the Baltimore checkerspot overwinters as larvae. In late summer, groups of larvae spin a communal pre-hibernation web-like nest of silk on the stem of a plant, where they can remain protected while they continue feeding for several months. As winter approaches, they leave this web and enter the leaf litter on the ground where they will wait until spring to continue developing.