Nature diary > Baltimore checkerspot colony

This beautiful butterfly has an different life history than many other butterfly species. Many butterfly species are pretty solitary except for mating: caterpillars live and grow and pupate pretty much on their own. Baltimore checkerspot caterpillars are gregarious, feeding in groups. They go their separate ways before pupating, but when they emerge, they don't disperse. Many of the adults stay in the fields where they were born. That's why Baltimore checkerspots are said to live in colonies.

I took these photographs at a checkerspot colony in West Newbury, Massachusetts. Happily, the checkerspot meadows there aren't mowed or treated with herbicides or pesticides by the town recreation commission that manages the land. Because they are colonial, you can observe the life stages pretty easily. Members of the Massachusetts Butterfly Club counted 30 to 50 caterpillars on different days in June at this site.

When I went to the meadow in late June, I was never able to observe more than a dozen caterpillars at once. So much for my powers of observation. Apparently I was too late to see masses of caterpillars, all the caterpillars I saw were dispersed, and likely ready to form a chrysalis. The adults were cooperative subjects. They posed for 10 to 15 seconds or so before moving on to the next perch. However, they picked the flimsiest grasses possible, stuff that swayed in the slightest breeze. I didn't observe them perch on flowers to nectar, only grasses, leaves, and the unopened Black-eyed Susan in the gallery picture.