On the 16th, while Bryan was at work, I headed out for my first excursion in some time, to the St. John's Conservation Area near Thorold for a bit of odonate-watching.
St. John's, admittedly, isn't exactly pristine wilderness. Its chief feature is a man-made pond stocked with trout (and, for some reason, Koi) for the edification of local fishermen.
For some reason, it has also been stocked with Red-eared Sliders (Trachemys scripta elegans), a native of the southeastern United States that certainly doesn't belong in the wild in Ontario. Surely, if turtles had to be brought in, one of our native species would've been a better choice?The pond did have some genuinely native wildlife: Green Frogs (Lithobates clamitans)...
...a few Mallards (Anas platyrhynchos)...
and, of course, fishes. The Pumpkinseed (Lepomis gibbosus) is one of the best-known of the North American freshwater sunfishes, members of the peculiarly North American family Centrarchidae. Othe centrarchids include the black basses of the genus Micropterus, widely introduced as game fish in other parts of the world. Despite their names they are not related either to sea basses (Serranidae) or to the truly weird and completely different-looking oceanic sunfishes (Molidae).The words surrounding the pond are attractive enough, and boast stands of Tuliptree (Liriodendron tulipifera), a Carolinian species at the northern edge of its range. However, most of the streams in the woods seem to have dried up, and even a spring-fed pond produced only the briefest glimpse of an unknown dragonfly that took off on my arrival and never returned.
That left me with the edge of the trout pond itself, here, I only found two species of dragonflies (except for a probable darner that put in a brief appearance over the creek feeding the pond): Widow Skimmers (Libellula luctuosa) at one end…
...and Common Whitetails (Plathemis lydia) at the other. Males of each species chased each other vigorously along the pond edge in what seemed to be almost ritual patterns, regularly returning to the same perches before starting over again.
I had seen both of these dragonflies only a few weeks earlier at Stoney Lake. That left the real excitement (at least as far as I was concerned) to the damselfly contingent. I found three species at the pond, two of which were new to me - indeed, I was able to photograph all three from the same spot at the pond edge. Commonest were Variable Dancers (Argia fumipennis), rather dull violet-striped insects that could be remarkably hard to pick out through the viewfinder as they sat on the gravel path around the pond.
Much more colourful, but equally frustrating to photograph - it took a long time for them to settle down, and once they did they were as likely as not to take off again before I could bring my lens to bear - were Eastern Forktails (Ischnura verticalis). The males are attractive and conspicuous insects, and even when they are not close enough to see in detail the bright blob of green at the front end and equally, or even more brilliant, blob of blue at the tip of the abdomen shine out as they fly by in the sun.A few of the males that I saw indulged in an odd display on landing, curling and flicking abdomens vigorously up and down.
Female Eastern Forktails will curl their abdomens downward to discourage amorous males, but that obviously doesn't explain what these males are doing. It is possible that this is a stage in the transfer of the male's sperm to his secondary sexual organ, but I can't be sure of that!
Smaller, and harder to spot, was a third species of damselfly, the delicate little Fragile Forktail (Ischnura posita) . Its best mark, if you can see it closely enough, is the "exclamation point" performed by the broken humeral stripe (the streak along its shoulder) on the thorax. I suspect there were quite a few of them about, but they seemed to spend more time hiding in the pondside vegetation than their larger cousins.
The most striking insect around the pond was not a dragonfly but a butterfly, the Red-spotted Admiral or Banded Purple (Limenitis arthemis). Besides being large and handsome, this is a most interesting insect. It comes in two colour forms so different from each other that they were once considered separate species. The other, which carries a broad white ban running vertically across both the fore and hind wings, is usually known as the White Admiral.
The dark form I saw at St. John's is a mimic of the unpalatable Pipevine Swallowtail (Battus philenor), while the white-banded form, commoner in the southern parts of its range, does not appear to be a mimic of anything. To make matters more confusing, the species hybridizes on rare occasions closely-related but extremely different-looking butterfly, the Viceroy (L. archippus), famously a mimic of orange-and black milkweed butterflies including the Monarch (Danaus plexippus).
Like many (usually male) butterflies, Red-spotted Admirals descend to the ground in search of mineral salts (and are often easiest to approach, and photograph, there). This one is sharing the delights of a local gravel patch with a particularly unique (and uncommon) little insect. It is a Harvester (Feniseca tarquinius), and it's caterpillar has the distinction of being the only carnivorous butterfly larva in North America.
"Harvester" is a direct translation of this butterfly's generic name, Feniseca. It is a member of the Lycaenidae, the Blue and Hairstreak family, but it is certainly not a very typical one. Its caterpillars feed on aphids, and their carnivorous diet helps them grow quickly through the larval stage - they can mature in as little as eight days, moulting only four times, one less than in most other butterflies. The adults feed on dung and tree sap, and visit aphids to sip their honeydew. Tha Harvester belongs to the subfamily Miletinae, all of which are either carnivorous as caterpillars or live on secretions from aphids and their kin. Its nearest relatives are in eastern Asia; in North America, there is really nothing else like it.