Commas and cloaks

Adult Eastern Comma (Polygonia comma)

What: It's been a busy couple of weeks wrapping up my semester at CCV and starting to wrap up at Crow's Path for the Spring. Today I did find a cormorant skull, that I'll post photos of in a few days. In the meantime, enjoy these photos of an eastern comma and a mourning cloak. They're among our first butterflies to emerge in the spring. Now with the prolonged warm weather and appearance of more and more flowers (how about all that celandine along the bike path, marigold along mucky drainages, and gorgeous and subtle green flowers of striped maple?) there are many more adult butterflies and moths appearing.

Overwintered adult mourning cloak (Nymphalis antiopa)

Ecological notes: While out in Centennial Woods a couple of weeks ago I was watching a couple dozen or so mourning cloaks flitting around. Occasionally they'd come into another's territory and they'd spiral whimsically up into the sky together. It was elegant and graceful and then the awkward comma would get all huffy and jump into the mix. At first it seemed confused, like it didn't know that the mourning cloaks weren't possible mates. But then it seemed more like it was getting angry that the mourning cloaks were in its breeding area and was just trying to chase them away. The tiny drama was endearing in that condescending, anthropomorphic kind of way.

Both species breed in the spring, and this is the only time of year this territorial behavior is observed. Apparently my theory of defending breeding areas has largely been dispelled in recent years according to a local entomologist, but it seemed the easiest and most obvious explanation. More appealing than, "the commas get confused and can't tell the mourning cloaks from a female comma").

Where: Centennial Woods

Monster of the dill

What: Last night I spotted a black swallowtail caterpillar (Papilio polyxenes) on our dill. When I came back this morning it was still there, perched on the same delicate pedicel (fancy name for the stalk that connects a flower to the main stem of the plant) of the dill's umbel (fancy name for an inflorescence [fancy name for a cluster of flowers connected by a central stalk to the main stem of the plant] where the flower stalks are of equal length and extend from a central point).

Prolegs on left, 6 legs on right

Ecological notes: I read two things about these caterpillars. The first is that they can decimate a patch of dill when their populations erupt, and they often do, in near biblical proportions (exaggeration, but warranted for gardeners with an affection for dill; in the photo to the right you can see all the "missing" flowers at the tips of the pedicels from where the munchkin gnawed them off). Many of their would be control-mechanisms, like birds, are thwarted by what's called an osmeterium, a weird little forked appendage at the front of the thorax (just behind the head). When provoked the caterpillar will rear up dramatically on its prolegs extend the osmeterium and emit a most rank and foul odor. Well, I had to test this out myself. I didn't smell anything except freshly cut dill (you can see a bunch of flowerless stalks that the caterpillar had nipped off), but what a beautiful treat! Perhaps the vibrant orange signals as a warning before emitting the odor, much like a skunk stomps its feet, chatters its teeth, and does a handstand before finally spraying an approaching predator.

Where: My backyard

Etymology notes: The root "osme" comes from the Greek ὀσμή, or "to smell" and the suffix "-rium/-ria" indicates a place or building (e.g. atrium, cafeteria, solarium).

Dragonflies and Butterflies

What: I have been seeing this beautiful, big, white-bodied dragonfly with distinct striping on its wings for over a month now in Centennial Woods. I could tell immediately that this was a dragonfly and not a damselfly (the other major group of Odonates) because of its large abdomen and broad four translucent wings that lay flat when at rest (a damselfly's wings would rise up vertically). I once worked with an ecological researcher who studies dragonfly behavior, but I couldn't remember for the life of me what this particular one was. Was it a darner, a skimmer, a cruiser, an emerald (common groups of dragonflies)? So I scoured the internet trying to remember what this very common white-tailed dragonfly was, and lo and behold, it is the Common Whitetail (Plathemis lydia, formally Libellula lydia). It is so common, in fact, that it is found in all of the 48 conterminous United States and most of the Canadian provinces.
            As for the butterfly, it didn't take too long to identify it using this site: http://www.thebutterflysite.com/vermont-butterflies.shtml. I took a look at the names for the different butterflies, and noticed that there was a group called "Swallowtails." If you look a the photo above, you'll see that is a fitting name for this kind of butterfly. Then I looked through the names of Swallowtails, and noticed there were two species named "Tiger Swallowtail," again, the yellow wing with black striping suggests such a name would be apt. One is the Canadian Tiger Swallowtail (Papilio canadensis), and the other is the Eastern Tiger Swallowtail (Papilio glaucus). I tried to read a little bit more on distinguishing the two, but the most common trait identified was the smaller wingspan of the Canadian, which is not of much help to meet with this one fleeting photo I captured. I am happy with my Papilio classification - you can add more if you'd like!

Ecological notes: Common to members of the Odonata, the Common Whitetail dragonfly starts off life as an aquatic "nymph." You'll remember seeing dragonfly and damselfly nymphs in collections of stream macroinvertebrates if you ever did those exercises in school! This particular dragonfly nymph is tolerant to polluted waters, so it is not used as an indicator of stream health (although it doesn't mean the stream is unhealthy if they are present). Both the nymphs and the adults feed on other insects, so remember to not be afraid of these possibly intimidating insects, as they will help keep those mosquito and black fly populations in line!

Where:  I encountered this breeding male (as denoted by the starch-white abdomen) basking on the boardwalks that run through the powerline cut in Centennial Woods, close to the stream. This is really where it thrives, as it is after mosquitos and other insects that are found around ponds and slow-moving streams. This male stayed very close to one piece of boardwalk, and that is also a common behvaior, as breeding males with guard a 10-30 meter stretch of river or pond side as their territory. I saw another male Whitetail about 100 feet up the trail on the other side of the stream, most likely guarding its territory.

Other notes: It was fun to finally explore more of our charismatic minifauna, as I think these two are both beautiful and showy, albeit small in size. These are two great insects to get to know, as they are apparently very common throughout North America. Now it's time to explore more butterflies and dragonflies. Be on the lookout for the Vermont state butterfly - the Monarch - on its massive migration to feed on milkweed later in the summer!