Mylitta Crescent butterflies are fairly common in Oregon and unlikely to face hardship any time soon because they lay eggs on, and the larvae subsist on, thistles.
The name Mylitta is the Greek translation of an Assyrian goddess of fertility called Mullissu. I don’t think the butterfly is any more fertile than most, but females can lay more than 250 eggs at a time on the undersides of thistle leaves, and they have more than one generation per year.
At Mount Pisgah, Phyciodes mylitta have a fairly long adult season, flying into late summer and at least into mid-October. They spend the winter as late-stage larvae, and apparently they wiggle out to bask on sunny winter days. So look near thistles for small, bristly black caterpillars in the coming months.
There are several kinds of Crescent butterflies in Oregon, and teasing out which is which can be confusing. Mylitta Crescents are small, with wingspans of just an inch and 1/8th or so. The colors and markings on the upper wings can differ widely. A couple of sources say the males are more variable. The lower under-wing has a prominent silver crescent on it, hence the name. The antennae are striped, with a plucky orange matchstick tip.
Take a moment to count the legs on the P. mylitta profile view. Yes, that’s right, there are four. Crescents are in the Nymphalidae family of butterflies, aka brush-foots. Monarchs and Mourning Cloaks are also part of the family. Their diminished, bottle-brush-like front legs fold up, barely visible just under the eyes, and the insect doesn’t use them to stand or walk. Which begs this column’s thought problem: What advantage does this give them? One of the sources below has some interesting ideas, including that the legs developed other senses like taste and touch.
See more of Karen’s work here.
Ray Cannon discusses why Nymphalidae front legs are diminished: https://rcannon992.com/2020/03/25/forelegs-and-four-legs-in-butterflies/comment-page-1/. Accessed 10/20/21.
General information from Montana: https://fieldguide.mt.gov/speciesDetail.aspx?elcode=iilepk3090. Accessed 10/20/21.