South March Butterflies

Little Glassywing

On July 5th I headed over to the South March Highlands to check the open milkweed field at the Klondike entrance for butterflies. It was a little earlier than my visit last year when I added the Striped Hairstreak to my life list on July 13th, but after having seen a Banded Hairstreak at the Rideau Trail yesterday, I figured the large milkweed patch might hold a few surprises.

I arrived at 10:00 am, and it was already heating up a tad uncomfortably – the daily high temperature hasn’t dipped below 30°C this month so far, and the forecast called for another 30°C high today. It’s great weather for looking for bugs, although they, too, retreat to the shade during the hottest part of the day when the temperature becomes unbearable.

When I reached the open area beyond the woods at the Klondike entrance I was delighted to see the flowers abuzz with insects. Many small bees and butterflies were busy gathering pollen or feeding on the nectar, and I carefully waded into the milkweed to look for hairstreaks and other bugs of interest – individual Wild Parsnip plants were also growing among the milkweed, and I had to be careful not to touch any part of the plants for fear of burning my skin. The first insect that caught my attention was not a bee or a butterfly, but a pretty flower longhorn beetle.

Flower Longhorn Beetle (Etorofus subhamatus)

Although it looks quite distinctive with the four yellow areas on its elytra, it must not be very common as it doesn’t have a common name. It belongs to the same tribe of flower longhorns as the Banded Longhorn beetle (Typocerus velutinus), a species I’ve seen in a number of places, including Petrie Island, Bruce Pit and the South March Highlands.

Although I wasn’t particularly looking for dragonflies on this visit, one whiteface caught my attention. It, too, seemed to be interested in all the activity in the milkweed, though it was looking for prey to eat rather than subjects to photograph! At first I wasn’t sure what it was, as the spots on its abdomen were somewhere between red and yellow – most immature whitefaces have yellow spots, and these either disappear or turn red depending on the species. Further complicating the identification of this individual was the large wash of amber on the basal area of both sets of wings (basal = closest to the body). After sending my photos to Chris Traynor, he came up with the ID of Dot-tailed Whiteface – a dragonfly so common that I tend to look for them only when seeking species to add to an iNaturalist project, or when it seems they should be present but aren’t (for example, the Eagleson Storm Water ponds). Chris noted that in the Paulson field guide (“Dragonflies and Damselflies of the East”), there is a picture of an immature Dot-tailed Whiteface with extensive amber-based wings. The text even notes that pale, immature females with amber-tinted wings may be confused with the Band-winged Meadowhawk. With the yellow spots running down the length of the abdomen I knew it wasn’t the meadowhawk, but it made me happy to learn something new about even one of the most common and familiar species in our area.

Dot-tailed Whiteface

After I was done photographing the whiteface, I returned to my search for butterflies. A Great-spangled Fritillary landed briefly on a leaf, then flew off without stopping to feed on the milkweed. A little later I found my first (and only) hairstreak – from a distance they look small and brown, darting out from a perch to chase after another bug or flying quickly from flower to flower. Only once you get up close or take a peek through your binoculars will you see the colourful blue and orange spots along the edge of the hindwing and the white stripes or circles in the center of each wing. Hairstreaks always land with their wings closed, and identification is fairly straight-forward for most of the species in our region, except for two: the Hickory and Banded Hairstreaks. I followed this individual around for a while, trying to get some clear shots so I could identify it. When I got home, I thought it was a Banded Hairstreak, as the blue spot on the hindwing doesn’t project that much further beyond the orange spot above it. However, I was wrong.

Hickory Hairstreak

After being corrected on iNaturalist, I delved into the realm of hairstreak identification. The article “Identifying the Hickory Hairstreak” by Mike Nelson (published by Massachusetts Butterflies) is very helpful in describing what to look for. First the author notes that the wing pattern of individual Banded Hairstreaks is quite variable, which means that any single field mark is usually insufficient to distinguish this species from the Hickory Hairstreak. He then points out four field marks to look at in conjunction with one another:

1. First, the orange and black spot at the base of the hindwing is distinctly smaller than the blue spot below it in the Hickory Hairstreak and has a smaller orange cap. In the Banded Hairstreak, the orange cap together with the black center is almost the same size as the blue spot. (This field mark points to Hickory Hairstreak in the image above.)
2. On the hindwing, the three spots in near the top of the hindwing (forming the postmedian band) are usually wide and aligned with each other in the Hickory Hairstreak. In the Banded Hairstreak these spots are usually not aligned together and are quite narrow. (These are wide and not perfectly aligned, but more aligned than that of a Banded Hairstreak.)
3. The inner spot closest to the top of the hindwing is wide and usually aligned with the inner spot below it in Hickory Hairstreak, but narrow and offset from the inner spot below it in Banded Hairstreak. (Again this is wide and not perfectly aligned with the spot below, but more aligned than that of a Banded Hairstreak.)
4. The spots at the top of the forewing are usually wide in Hickory Hairstreak, and narrow in Banded Hairstreak. In addition, the three spots at the top are usually wider than the two spots near the lower edge of the forewing in Hickory Hairstreak, while they are all the same size in Banded Hairstreak. (These spots appear wide but the three spots above are not noticeably wider than the two below.)

The Nelson article mentioned above contains labelled photographs illustrating each of these field marks.

Happy to have found one hairstreak, I set out about looking for others. I saw a few dark skippers fluttering close to the ground but didn’t pay much attention to them, assuming they were all Dun Skippers. Then one slowly opened its wings and I realized that it had several large, white spots in the middle of the forewing. It wasn’t a Dun Skipper after all, but a Little Glassywing – a new Ottawa species for me!

Little Glassywing (female)

This species closely resembles both the Dun Skipper and the Northern Broken-Dash; the females of all three have white spots on the forewing, though the spots are translucent in the Little Glassywing and opaque in the other two species. These spots are particularly large and squarish in the female compared to the male, and if this hadn’t been a female I’m not sure whether I would have noticed. Males show three large golden spots across the forewing, the middle spot being a trapezoid shape. Female Northern Broken Dashes and Crossline Skippers also have large yellow spots in the middle forewing, but they lack the distinctive trapezoid shape as well as the glassy/reflective quality. 

Another field mark to look for is the white patch just below the club of the antennae (difficult to see in the images above and below).

Little Glassywing

It flew off, and I managed to get a view from the side when it landed – fresh individuals such as this appear reddish-brown and show a pale band of spots on the hindwing. The Little Glassywing has been moving northeast from its traditional breeding grounds south of Lake Simcoe over the last decade. I saw my lifer at Murphy’s Point Provincial Park in 2014 one rainy day where I noticed it resting in the vegetation along the Beaver Pond loop of the Silver Queen Mine Trail. Its prefers wet meadows and grasslands, especially near wetlands and forest edges. They often visit milkweed and are known to be avid mud-puddlers.

Little Glassywing

Eventually I left the milkweed field and continued on my way to the boardwalk to see what might be lurking around the water. I found a lovely pale violet Blue Flag Iris right beside the trail; normally I see these flowers in June, when they are dark purple with brilliant yellow streaks. These flowers often attract insects, and its always fun to photograph them and later discover an insect or two lurking in the petals on my images at home. I had no such luck this time.

Northern Blue Flag

I also found a Dun Skipper mud puddling on the ground. This male shows no spots and has the typical bright golden head of the species.

Dun Skipper

There wasn’t much at the water so I returned to the milkweed patch again. This Northern Crescent posed nicely for me on the pink blossoms; this is one of the easier individuals to identify, as the large open area on the hindwings show none of the black lines that would be seen in the Pearl Crescent.

Northern Crescent

On my way out I saw a large swallowtail fluttering among a smaller milkweed patch growing in a small open area between the path and the trees. At this time of year the Canadian Tiger Swallowtail has stopped flying, and the Midsummer Tiger Swallowtail (believed to be the descendants of a long-ago hybridization between the Canadian and Eastern Tiger Swallowtail) is now on the wing. The marginal band close to the edge of the forewing consists of distinct yellow spots; this is similar to the Eastern Tiger Swallowtail, which we do not get this far north, and rules out the Canadian Tiger Swallowtail which has a continuous yellow stripe instead.

The Midsummer Tiger Swallowtail ranges across Southern and Eastern Ontario, meeting the Eastern Tiger Swallowtail at its northern edge and the Canadian Tiger Swallowtail at its southern edge. And just as this new species appears between the two ranges of its parent species, it appears between their flight seasons as well. The single-generation Canadian Tiger Swallowtail flies in late May/early June in most of its range, while the first generation of the Eastern Tiger Swallowtail flies during the same timeframe and the second generation starts flying in August. The Midsummer Tiger Swallowtail emerges in late June to early July – just when the other two early-emerging species are dying off.

Midsummer Tiger Swallowtail

The butterfly spent some time fluttering from flower to flower, flapping its large wings to support its body as it fed. The larger, heavier swallowtails – including the Giant Swallowtail – often have this issue, which makes it difficult to photograph them as they are feeding. It is much easier to photograph them basking on a leaf in the sun, or sipping moisture from a mud puddle, but these don’t usually make for pretty pictures!

Midsummer Tiger Swallowtail

I was happy with the diversity of butterfly species I found in such a small portion of the South March Highlands. This conservation area is definitely worth further exploration, but with 450 hectares to explore and several kilometers of trails leading deeper into the conservation area, it would take a long time to discover all the places they like to gather (for instance, any more milkweed fields within its boundaries). In the meantime, the milkweed field off of the Klondike entrance has turned out to be a great spot, and I plan on returning again next weekend to look for more hairstreaks!

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