In summer, this decreasingly young man’s fancy lightly turns to bugs. Specifically, the middle weeks of July are when the annual “4th of July” butterfly counts are held. These one-day affairs are much like the Christmas Bird Counts — an all-out annual blitz of a 15-mile circle to count things that fly around. The counts happen all over the continent and are run by the North American Butterfly Association — hopefully, you haven’t let your membership lapse. On the Cape and Islands, there are counts centered in Falmouth, Brewster, and Truro, all of which were held in the last three weeks. To anticipate your first question, yes, Monarch numbers are low this year, likely due to weather events to our south.
So how, and why, does one count butterflies, anyway? The data in aggregate can be used to study population trends at bigger scales. And doing these counts well requires knowing not just the expected species but also their habitat affinities. Like many insects, butterflies have specific and intimate relationships with particular plants, either for drinking nectar, laying their eggs, or both. Knowing those relationships, you focus your efforts where the appropriate plants are.
Yes, Monarchs need milkweed for their caterpillars to eat, but did you know Mourning Cloaks and Viceroys need willows? Or that Tiger Swallowtails need wild black cherry? Or that American Ladies here mainly lay eggs on an inconspicuous little composite called Sweet Everlasting, something you’d probably pull if you saw it in your yard? The overall most important host plants for butterflies around here are native grasses, oaks, cherries, and willows. Understanding these relationships will have you looking at our natural and neighborhood plant communities with fresh eyes – as important as they are as an ambassador species for insect conservation, there’s more under the sun than Monarchs and Milkweed.
For example, just a handful of red maple swamps around here have the right combination of sun and tree canopy to satisfy the Appalachian Brown, which is an actual butterfly and not a bluegrass singer, whose caterpillars eat a grassy wetland plant called tussock sedge. And you won’t find the diminutive Bog Copper outside a wild or abandoned cranberry bog, where they drink nectar from and lay their eggs on the cranberry plants. Similarly, you won’t find handsome little Edward’s Hairstreaks far from shrubby patches of bear oak, where their tiny caterpillars secrete a sweet honeydew for Allegheny Mound Ants in exchange for their protection.
In a hopeful sign of nature’s resilience, many butterfly species have adapted to use ubiquitous non-native species as host plants for their caterpillars. The Broad-winged Skipper only uses the invasive reed Phragmites, and Wild Indigo Duskywings have learned to use invasive crown vetch. The stunning Baltimore Checkerspot now uses the lawn weed English plantain in addition to the obscure wetland plant they used before – as a result, they went from a declining species to one reaching Biblical plague numbers at places like Marstons Mills airport.
It's not just, or even mostly, about butterflies for me. As an all-around biodiversity enthusiast, I view the counts as a chance to get out into habitats where I might find interesting plants, birds, bees, or other insects, as well as the butterflies. Finding a rare bee or an orchid I’ve never seen gives me more of a buzz than counting the butterflies.
By now I’m sure you are saying “How can I get into this stuff so I can be just like you, Bird Guy?”. Apps like Seek and iNaturalist make it easy to start identifying many of the plants and bugs around you, but be careful – it can be addictive. Find the Mass Butterfly Club website and join a walk. You really should look into this butterflying business. Despite what you might think, it’s not just for eccentrics who gambol about in meadows with funny hats and pants tucked into socks. Sometimes we wear shorts.
