Close Encounters with Dragonflies in mid-January

The New Year started off with some serious winter weather, but Mother Nature has given us a break for the past three days, with the temperatures hovering around a more bearable 5°C, plus or minus a degree or two. As good a time as any to take advantage of the moderate meteorologic conditions and search for whatever dragonflies might be out and about.

The woodland stream depicted in the next photos is along the trans-Canada Trail, roughly half a kilometer east of Tweed. This is the view looking north of the trail.

And it didn't take long to find a dragonfly. She is 30 mm in length, and it definitely is a girl – the tiny ovipositor can be seen peeking out between abdominal segments eight and nine.

A photo of the stream to the south of the trail, and again, a few scoops of sand and silt from the stream bed produced a pair young males. The larger of the two is 25 mm long, the other little guy is 18 mm in length.

This is the same site where I found the Spiketail naiads last August, and I know there are lots of them lurking in the bottom of the stream. The real purpose of this excursion was not to look for dragonfly naiads, it was to satisfy my curiosity as to what they might be eating. Are any of these insect species food for Cordulegaster larvae? I don't know for certain, but given what I've read about odonate larvae in general, they are voracious eaters and will take whatever they can capture and overpower.

There are some mayfly naiads inhabiting the stream but they are not common. Caddisflies are a bit better represented, I found two species, a small one that makes its protective casing out of grains of sand, and the larva in the following photo. (Incidentally, the insect was pulled from its case by accident, I didn't tear it out for the sake of a few pictures.)

I think the caddisfly larva is probaly genus Triaenodes, at any rate both the insect and its casing strongly resemble the one in the next photos (taken during the much warmer days of a summer long past).

There were also some stonefly naiads hiding in the leaf debris along the steam's edge. Like the mayflies, they are not common, and they are tiny, almost translucent, only about 5 mm long. Not much of a meal for the naiads that I dredged up, but good enough to feed a hatchling.

The most likely source of nourishment for the growing young Spiketails are the large, maggot-like critters in the following images. Based on their aforesaid "maggot-like" aspect, I surmised (as it turned out, correctly) that they might be cranefly larvae, indeed, I think they are the larvae of the Giant Crane Fly (Tipula abdominalis). The stream bed is teeming with these detritivores and one scoop of muck can yield half a dozen. They are large, normally chunky, oval shaped and grub-like in appearance and about 25 mm long, but can extend themselves to 40 mm or 60 mm.

The insects didn't like being out of their element and weren't co-operating, so this is best macro I could obtain of the spiracular lobes. Here's a link to some much better images at BugGuide.Net.

This is an old photo from a few years ago of the adult fly, not an uncommon species, and aptly named too.

The air was warm enough to permit some active insect life outside the insulating confines of the water and there were a few small black midges flying around. And before I left for home I saw this on the snow ...

A little Long-jawed Orbweaver spiderling, no longer than 3 mm. No matter how tough the circumstances or adverse the conditions, life goes on ...

To see a World in a sample of Pond Scum

The strange and weird things one learns from the most mundane circumstances.

The green growths on a stone fished out of the Moira River are colonies of – I'm still not entirely clear which – either a blue-green cyanobacterium called Nostoc parmelioides, or an algae composed of the bacteria.

This organism is symbiotic with a tiny species of midge called Cricotopus nostocicola, the larvae of which develop in the algae, changing its form from small round growths to a semi-circular shapes; both versions can be seen in this picture. The Cricotopus larvae are supposed to be visible within the semi-circular colonies – how large are they, and is my camera's macro good enough to capture an image?

Ancient ancestors of cyanobacteria oxygenated our planet's atmosphere about 2½ billion years ago. Prior to the "Great Oxidization Event" Earth's early atmosphere was believed to consist of gases much like Saturn's moon Titan, hardly conducive for life on Earth as we know it today. The oxygen in the atmosphere also combined with the extant minerals to form new mineral species.

Some cyanobacteria play a role in nitrogen fixation, some are symbionts in lichens, they live in the fur of sloths, and on the negative side they can cause toxic algal blooms. It isn't stretching the truth to say that cyanobacteria were a major force in the shaping of this planet and the life upon it – we literally wouldn't be here without them – and they continue to play significant roles in the tangled webs of its ecosystems.

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Re-visting the river a couple of days later in the hopes of finding some Cricotopus larvae, or whatever midge larvae are called ... midge maggots?

Blue-green algae or cyanobacteria ... other than that I have no idea what this stuff is, or even if it's all the same species. Sometimes it's found growing in tangled masses of filaments, or it may be organized in lacy branches.

Still hard at work after billions of years ... the bubbles trapped within this mass of blue-green algae are presumably oxygen. There was also evidence of lots of decayed algae, the decomposition process presumably using up the some of the aforementioned oxygen. Increased amounts of nutrients such as phosphates can cause the cycle of phytoplankton growth and decay to spiral out of control, initiating a process know as hypertrophication.

Getting back to the Nostoc parmelioides cyanobacteria and their Cricotopus spp. insect partners – I removed and examined some of the bracket-shaped growths and the midge larvae are naked-eye visible within the algae. The insect is coiled in a spiral with its head near the center of the circled area. The roughly circular shapes are about 5 to 6 mm across, and the larvae fully stretched out are 3 mm long at the most.

I also dissected a couple of the growths and managed to acquire some half decent macros of the Cricotopus larvae. It's no mean feat to peel the algae apart without damaging or killing the tiny insects using a jack-knife as a dissecting tool.

While studying and photographing the algae it was impossible to miss the uncountable numbers of what appeared to be very small, perhaps 4 mm long, caddis fly casings attached to the rocks at the bottom of the river. The closest match at BugGuide.Net is Brachycentrus appalachia, but it's pushing it to identify these diminutive insects to the species level based on the paucity of detail visible in the pictures.

All this "R&R" – research and reading – because I paused for a moment to indulge my curiosity and photographed some "scum" sprouting on a rock in the river ...