I’ve recently been hired to survey a piece of land out near Carleton Place. I’m there to inventory their birds, but I find my attention regularly wandering to the many other interesting things I encounter while hiking the site. About half of the land area there is open field, which has been leased to a nearby farm and is lightly grazed by a herd of perhaps 20 horses. The gentle land use has helped maintain the site as a lush meadow full of wildflowers and rambling growth. Beautiful, diverse meadows like this aren’t very common; certainly the fields on our property lack this sort of verdant vegetation.
My surveys are intended particularly to discover whether Species at Risk are present. The meadow type doesn’t contain enough grass to be especially appealing to Bobolink, and there are only a couple pairs of Eastern Meadowlark, and it’s far too grassy to interest Common Nighthawk; there aren’t enough shrubs to draw in Golden-winged Warblers, and not enough of what shrubs there are are hawthorn to make it appropriate for Loggerhead Shrike. I suspect the list of Species at Risk will end up being a little on the thin side, which is too bad, because it’s the presence of those species that results in protection for all the rest of the species that use the site. And this is a beautiful site.
On previous visits I’ve been there on overcast mornings, but this weekend was clear and warm. I started with the forested bits first, and by the time I made it out to the meadows, about three hours after sunrise, the vegetation was all drying off and the insects were perched at the top of the plants, absorbing the sunshine and preparing for an active day. As I walked through the thigh-high growth my passage stirred up clouds of small orange skippers – dozens of them at a time, floating lightly just above the flowers. I felt like I was walking through a fairy tale.
In many spots they clustered on the flowers – especially the milkweed, but also the Viper’s Bugloss. They seemed to be actively sipping on the nectar of the milkweed, though others simply rested on the stems of grass they perched on.
Every single one of them, or at least every single one that I looked at, was a European Skipper, Thymelicus lineola. These little butterflies are, as the name says, not native. They were introduced to North America around 1910, in a shipment of contaminated Timothy grass seed. Adults lay their eggs on the leaf-sheath or the seed heads of Timothy and a few other grass species. The butterflies spend the winter as eggs, the only North American skipper species to do so. As you might expect, eggs built to overwinter are particularly hardy, and European Skipper eggs will even survive modern seed-cleaning methods.
The species has spread on its own, but it’s been helped along by the distribution of contaminated Timothy seed. This site relates that during the building of the James Bay Highway in the 70s roadsides were stablized using imported grass seed, including contaminated Timothy, thus bringing the skipper to northern Ontario. From its initial introduction a century ago in London, Ontario, the species now ranges over nearly all of northeastern North America.
In our area there are only two species of skipper whose wings are unmarked orange, bordered in brown: the European and the Least Skipper. The latter has much broader borders and a slightly different body shape (if you’re the sort to look that closely). I’ve seen a number of sources that describe the European as often ridiculously abundant in good habitat, sometimes outnumbering all the other skippers at the site combined. It’s also pretty widespread, since Timothy grass is found so commonly in both agriculture and other contexts.
Interestingly, it’s apparently possible to sex male and female European Skippers by the forewing pattern. Males are supposed to have a narrow black stigma, which is a marking roughly in the center of the wing. In looper moths it’s a spot, often hooked in shape. In European Skippers, it’s more like a thin, short dash that runs from just beyond the shoulder to the middle of the wing. I searched through all the individuals I took photos of and only found one that was clearly a male:
seabrookeleckie.com 
Wow! I’ve never seen so many skippers in one place before!
It’s an introduced species, so that bit’s not so good, but what an amazing sight. I see lots of skippers, but can’t get close enough to them for an ID most of the time.
Glad I found your blog, and glad I finally know what to call those little orange butterflies I see everywhere on our hikes!
A very interesting article! I saw thousands of these on Manitoulin Island last summer as well. They were also recorded in 2009 on the island. I wonder how far and wide these population explosions occur, since I didn’t see so many in southern Ontario. Interestingly, they just disappear in a few weeks. Great pictures too!
I’m not sure exactly why but this weblog is loading extremely slow for me.
Is anyone else having this problem or is it a issue on my end?
I’ll check back later and see if the problem still exists.