October 2010 – Page 2 – Seabrooke Leckie

Canada Darner

A few days ago Dan pointed out a dragonfly that was sunning itself on the screening of the window at the front of the house. Or at least, it looked like it was sunning, on the south-facing side with its wings spread. Dragonflies (and all insects) being exothermic, most of their body temperature control is achieved through exposure (or not) to the sun (some insects will shiver, too – you may see this in moths, for instance, on cooler nights).

It didn’t move, though, and I began to think maybe it was dead, the barbed feet still clinging to its final resting place. It did look a bit ratty, with a few nicks out of the delicate wings. It didn’t leave as I approached, or even as I reached out to grasp it. But as I gently folded the wings together over its back there was stiffness, resistance, that wouldn’t be there if the insect was dead. Holding the wings firmly, I lightly pulled on it to see if it would hold on to the screen; it did, and the legs moved feebly once detached.

So it was still alive, just sluggish from the cool night. I took a few photos but left it where it was. Half an hour later, presumably sufficiently warmed, it had left.

The large size of this dragonfly makes it a darner, and the dark body with two diagonal stripes on the thorax makes it a mosaic darner, one of the species in the genus Aeshna. There are more than a dozen mosaic darner species in our area, and they all look confusingly similar. Identification is usually best made with the critter up close or in the hand, but they rarely settle down for long and are frustratingly difficult to catch with a net, while in flight or otherwise. The vast majority of my identifications of this group have been made in situations such as this – sluggish individuals that are easy to get a photo of.

The ID for these guys depends primarily on two characteristics: the shape and colour of the thoracic stripes, and the same of the markings on the abdomen (particularly the segments closest to the body). The eyes can also be useful for species identification. Having the dragonfly in-hand, or having a photo of it, while you ponder the possibilities is really invaluable because it offers you the opportunity to check for small details.

In the case of this one, it has a very distinctive marking that no other species have: that little dot just on the inside of the front thoracic stripe. Also, the sharp hook on the front of the stripe itself. Both of these features identify it fairly easily as a Canada Darner, Aeshna canadensis. The majority of the mosaic darners are not nearly so easily identified, bearing more generic straight slines of varying widths.

I have two dragonfly guides: Stokes’ Beginner’s Guide to Dragonflies and Dragonflies Through Binoculars. I like the photos better in the first, but the species coverage and information are better in the second. There are a few other regional guides in print, some of which are very good, that I simply haven’t gotten around to picking up. At this point, though, I’m waiting for the new Peterson Field Guide to North American Dragonflies by Ed Lam. I’m not certain when it comes out, but Ed was contracted in 2006 with a four-year submission target (I think), which would make it within the next year or so. Ed is painting every single species. Males and females and colour morphs. I can’t even imagine the amount of patience such a task would require! But the guide looks to be beautiful and extremely usable once it’s done. You can check out samples of the illustrations at his website.

Canada Darners are late fliers. They first start to emerge in July, but they can be found on the wing through October, till we get into sustained periods of cold. Some species of darners are migrants, moving south in the fall to warmer regions. Those great swarms of darners you might sometimes encounter during the late summer and autumn might be migrant swarms, feeding before they push on (darners will also simply swarm where there’s really good eats to be had, though, and it can be hard to determine which type a particular swarm is). However, Canada Darners, as far as I know, are not one of the migrating species.

Interestingly, Dragonflies Through Binoculars notes that “this species darkens when cool”. I gather this isn’t the case with all species of mosaics, and would explain why this individual looked so muddy to me. Those thoracic stripes are usually sky blue and yellow-green. The abdominal markings are generally all blue. You can just see the colours starting to come out in the thoracic stripes – if that is indeed what’s happening here – though the abdominal markings remain brownish.

Aside from this guy, the only other dragonflies I’ve seen around in a couple of weeks have been meadowhawks, which seem to be the latest fliers around here, at least in any numbers. Soon, even they’ll pack it in for the year. It’s nice to enjoy these lingering traces of summer while they last.

Potter Wasp

It’s been very rainy here the last couple of days – since I finished and mailed off the moth guide, basically. As if the weather knew that I’d suddenly have lots of time for hiking about and enjoying the last of autumn. Since I haven’t been out (I’m very much a fair-weather hiker, or at least not a poor-weather hiker), here’s another photo I’ve had collecting dust on my hard drive for the last week or so.

I noticed this wasp on a short stalk of goldenrod as I was walking back from checking out the earth tongues. A wasp on a goldenrod is not in itself all that unusual. Wasps seem plentiful at this time of year, but they’re nearly all Polistes paper wasps. This wasp looked strange, and when I peered closer its pinched abdomen, with swollen, bulbous tip, was pretty obvious. I couldn’t recall having seen a wasp of this shape before (mud daubers also have very thin abdomens, but theirs are thinner for longer, and very distinct), so I took a photo and looked it up in my trusty Kaufman Guide to Insects when I came home.

As it nearly always does, the KGI had the answer. This was a potter wasp, most likely Eumenes fraternus, a widespread wasp of eastern North America. According to BugGuide.net, this species favours scrubby fields and forest edges, which is appropriate to the habitat I found it in, and can be found from mid-summer through fall at more northern latitudes like here. Adults feed on nectar, and are often found on flowers.

The name of the group, potter wasps, comes from their habit of sculpting their nests from mud. The cells of the nest are adorable little spherical creations with a flared opening that look like tiny clay jugs. These are provisioned with caterpillars or small sawflies, an egg is laid on the prey item, and then the chamber is sealed off until the new adult wasp is ready to emerge. Larval wasps will spend the winter in their pots.

Earth tongues

I’d just like to start by saying – the moth book is done! Done! I took it to the post office and mailed it off today, with much excitement (the clerk, whom I asked to take a photo as I pretended to put it in the mail slot, didn’t quite appreciate my excitement, I don’t think). Of course, the book’s not completely done. There’re many more steps yet to go even once the initial manuscript is prepared and finished – a fact that I didn’t truly appreciate until I was doing a book of my own. Once our editor gets the files I sent her, she still has to edit all our text, we need to make any revisions as required, then the contents go on to layout, come back to us for proofing (the trademark Peterson arrows get put in at this stage), and go back for final revisions, before ever a copy gets printed. Actually being involved in the production of a book has been rather enlightening, not least of all in the amount of time it takes to get a book from idea to store shelf. It’ll have been about four years, in our case.

So life finally returns to normal for me. For the last, oh, three months or so, I’ve been buckled down and focused on completing the moth manuscript. A lot of things have fallen by the wayside, and I’m looking forward to getting back to all those things I’ve been missing. Like the blog! I’ve had these photos since last week, fully intending to post them shortly after taking them (I’d also been expecting to wrap up the book before the Thanksgiving weekend).

Over dinner one evening last week, Dan asked if I’d noticed the interesting mushrooms growing down near our little bog/fen. I’d been down that way a couple of times in the preceding days, but hadn’t gone in too far, and hadn’t noticed any odd fungi in the part that I had traversed. He commented that they were just the other side, a whole patch of them, thin little dark things sticking up from the moss. I said I’d check them out the next time I went out. In the meantime, I brought down my field guide to fungi for him to look through and see if he recognized them.

He picked them out fairly quickly, and after going back to have a look myself I easily agreed. These are earth tongues, probably Common Earth Tongue, Geoglossum difforme, a common and widespread species. By his description I had expected them to be coral fungi, but they’re actually a type of sac fungus. It’s the same group of mushrooms that contains the highly prized truffles and morels, though the guide suggests that the majority of members are not so edible. Most fungi produce their spores individually and release them through pores or from gills; sac fungi produce their spores grouped within sacs, each sac containing several spores (the number varies by species, but the average is eight). You can see some neat images of Common Earth Tongue spore sacs under the microscope at this page here (it’s from the website of the author of the field guide I use, George Barron)

The method of dispersal also depends on the species, but earth tongues share the same general mechanism as morels. The type of fruitbody is called an apothecium, and the sacs of spores are layered on its outside surface. Immature spores are pigmentless, but mature spores develop pigment to protect them from UV while they are airborne. When the spores are mature, the sac bursts, projecting them into the air for the wind to catch and disperse. Apparently with some species, if you blow gently on the mushroom when the spores are ripe you can trigger the sacs into bursting, releasing puffs of “dust”. I didn’t try it on these ones, in part because I didn’t know to, but even if I had they were damp and tacky and probably wouldn’t have been releasing any dust anyway.

They were all growing in a small patch of sphagnum moss, a short distance from the edge of the bog/fen. From the way they were distributed it looked as though they had an association with the moss, but I suspect it more likely that the moss simply kept the ground there nicely damp compared to the surrounding dirt; there’s no mention of moss in the guide.

Sunday Snapshots: October scenes

Fall Colour — The front yard, with soon-to-be thumb blisters.

Forests in autumn always look best backlit.

Grackles — Flocks of icterids on the move. We had a few hundred blackbirds and grackles pause in our trees this morning.

British Soldier Lichen. Though they "bloom" all year, my anecdotal observation suggests they kick it up in autumn.

Milkweed Fluff — Santa Claus wishes making their way north.

White slime mould

Although for the last couple of months I’ve felt a bit like the donkey chasing the carrot suspended from a stick, I’m fairly certain that the moth guide manuscript will be tied up and finished early this week. In anticipation of life getting back to normal, I’ve been trying to get back to some of my normal routine. This includes occasional walks, which I’ve mostly foregone the last several weeks (much to Raven’s disappointment, though Dan’s been taking her regularly still – I really owe him a debt for helping me out with things while I’ve been busy!), and, hopefully, blogging. I’m not going every day like I used to yet, but I am getting out. And I’m going to start posting more frequently than the once-every-two-weeks schedule I’d been keeping lately.

This afternoon I just walked back into our fields and back. It wasn’t far, and at this time of year I don’t usually anticipate finding much. The fields are mostly quiet: the birds have moved on, the flowers have, for the most part, stopped blooming, and what insects there are are primarily grasshoppers with a few Lucerne Moths and meadowhawks thrown in. In October the walks are more about enjoying the autumn colours, and the scent of the fallen leaves.

So I wasn’t really looking to find anything, and was therefore surprised and pleased to come across the above. It was just beside the path, at the edge of a little patch of trees. The fact that it seemed to be trying to climb up a tiny seedling tree confirmed to me what it was even before I stooped for a closer look: a slime mould! (Or mold, depending on your nationality.) This makes #2 for me – I saw my first one, a Fragile Yellow Slime Mould, just this summer – and I was excited despite its rather unassuming appearance.

I believe this one is Mucilago crustacea. Unlike the summer’s species, this one doesn’t seem to have a common name (although the scientific name, with a bit of poetic license, might roughly translate to “Crusty Mucus”). The second part of the scientific name refers to the slime mould’s texture once mature – crusty and rough. Like all slime moulds, it climbs to an elevated spot in order to release its spores, where they will be more likely to be caught and carried by the wind. I just saw the one, but they can sometimes occur in small groups of half a dozen individuals in close vicinity.