Thursday, September 25, 2014

An Equinoctial Odonate

Perhaps post-equinoctial would be more appropriate, as this immature male Twelve-spotted Skimmer (Libellula pulchella) was encountered on September 24th, 2014 at the Tweed Fairgrounds (south-central Hastings County, Ontario).

The Twelve-spotted Skimmer is a summer dragonfly, the first local fliers were observed at the Vanderwater Conservation Area in mid-June, a couple of very old males on their last legs were sighted as recently as ten days ago. But this is a young dragonfly, as yet lacking the pruinescence on the abdomen typical of fully mature males, and to see one flying this late in the year – the second day of autumn – is unusual to say the least.

Striking Spiders

Striking – arresting the attention and producing a vivid impression on the sight or the mind, attracting attention by reason of being unusual, extreme, or prominent, conspicuously attractive or impressive.

A dazzling Dark Fishing Spider, arresting the attention of an observer by virtue of her size, from the cephalothorax to the tip of the abdomen she is a mere 20 mm in length. Dolomedes tenebrosus can attain a body size of up to 26 mm with the legs spanning 90 mm but this one is deflated after laying her eggs. Like most Pisauridae (a.k.a. Nursery Web Spiders) she stands guard over her brood until they a bit older and better able to fend for themselves.

The spiderlings have already been through one molt and the pale exuviae can be seen littering the nursery.

A couple of closeups of the female, with one of her offspring clinging to her abdomen in the second photo.

A friend brought this wondrous Wolf Spider to me for identification, but unfortunately for the spider it was DOA when it arrived. The body length of this particular female Tigrosa aspersa was 23 mm and the legs measured 70 mm across, however, these "wolfies" can reach a respectable 30 mm.

The spider did indeed produce a vivid impression on the sight and the mind – the person who killed it woke up in the night and found the spider crawling on them; I wasn't informed what part of their anatomy. They immediately dispatched it (this was not the intent or one of the definitions of "striking" in the title), but under the circumstances it's pretty hard to fault a person for being startled ...

The arrangements spider's eyes are unique to each family, and this one's eye pattern is typical of the family Lycosidae.

A marvelous Marbled Orbweaver, in my opinion this is by far the most beautifully colored and patterned spider I have ever encountered. Araneus marmoreus is small compared to the foregoing two spiders, the body measures about 20 mm and the legs are relatively short, but it makes up visually what it lacks in sheer bulk – conspicuously attractive or impressive indeed!

The Marbled Orbweaver featured above is a female, and she's gravid and ready to lay her eggs any day to start the life cycle of her kind anew. On the other hand the female Longjawed Orbweaver (Tetragnatha spp) in the following photo won't likely get her chance to pass her genes on to the next generation, that opportunity now belongs to the small wasp, only about 3 mm in length, that's clinging to the underside of the spider.

The image was acquired under poor lighting conditions and is a bit out of focus but the wasp's ovipositor, ready to deliver its egg (or eggs?), is clearly visible in the photo. It's interesting to note that the wasp is in a "safe zone" and the hapless spider cannot reach it with its jaws.

The picture has been uploaded to BugGuide.Net where hopefully someone can identify the wasp. As of now I have no idea as to the wasp's species (Ichneumon, perhaps?) or life cycle – does it lay one egg per spider, or more? Will the spider be paralyzed by the hymenopteran's venom, or will it continue to go through the motions as the wasp larva (or larvae?) consume it from within? Whatever the story may be, like everything else in the world of nature we can be certain it's fascinating and compelling, possibly even (from our human viewpoint) bizarre ... which are all synonyms for the word "striking".

Wednesday, September 24, 2014

A female Saffron-winged Meadowhawk

East of Tweed, near a patch of wildflowers along Lakeview Lane (44.478429°, -77.301881°) – my third sighting of a Saffron-winged Meadowhawk this year (the other two were at Dry Lake, south of Marlbank). Sympetrum costiferum is larger – this individual measured 38 mm – and darker than the average Sympetrum apt to be encountered in our area, and it has a habit of perching on the ground.

As with other Sympetrum, the female Saffron-winged Meadowhawks is orange (compare to the red abdomen and brown thorax of the male).

The veins along the leading edges of the wings are saffron colored and the pterostigmata are long and pale orange.

Closeups of the face ...

... and its genital plate, a part of the dragonfly's anatomy that is unique and distinctive for each species.

Saturday, September 20, 2014

Amethyst Aster (Aster x amethystinus)

A hybrid between two very different looking species, the New England Aster (Symphyotrichum novae-angliae) and the Heath Aster (Symphyotrichum ericoides), the Amethyst Aster (Aster x amethystinus) exhibits characteristics of both parent plants which, not surprisingly, were abundant in the high and dry field where the Amethyst Asters were encountered.

The following groups of three photos illustrate the features of the Amethyst Aster, New England Aster and the Heath Aster respectively.

The overall aspects of the plants.

The blossoms resemble those of the New England Aster but are only about half as large and bear fewer ligulate flowers.

Even the involucral bracts or phyllaries are intermediate between those of the progenitor species.

More studies of the Amethyst Aster – the relatively small leaves are crowded and clasp the stem.

The main stem of the plant is hairy.

Wednesday, September 17, 2014

A Late Season Common Whitetail

Encountered west of Tweed near a marsh bordering the trans-Canada Trail (44.46889°, -77.31528°) – a surprising find as the final few surviving Common Whitetails (Plathemis lydia) were flying nearly a month ago, and no others have been sighted until now. The last sighting in this area was a male on August 18, 2014 near the intersection of River St. and the trans-Canada Trail (44.473668°, -77.312911°).

The dulled colors aside, this female is in really good condition with no wear and tear on the wings, it was extremely wary and alert and it sure could fly. Half an hour of patient stalking were required to capture the agile odonate.

As of today – September 17th, 2104 – the dragonfly is still alive and well. Sad to say, her days are numbered. Even if she manages to evade the Darners patrolling the marsh (six species currently known – and lots of them!) the first frost of autumn lies in the not too distant future ...

Adult dragonflies can live for a few weeks if they don't fall victim to predators or the elements. Looking at the lackluster colors of the eyes and thorax and the frayed wings of this male Common Green Darner (Anax junius), one can only wonder how old it might be.

An superannuated female Lance-tipped Darner (Aeshna constricta). Again, the coloration and patterning – originally a beautiful yellow-green – is obscured, the cerci are broken, and the wings have obviously seen their fair share of use and abuse.

The colors of this male Canada Darner's (Aeshna canadensis) are fairly bright and only the whitish discoloration and ragged edges of the wings suggest its age.

The dragonfly's face, however, was something of a shock – the brown clypeus is hardly typical of this species. Discoloration of the exoskeleton due to old age? Or an aberrantly colored individual?

Tuesday, September 16, 2014

Lake Darner (Aeshna eremita)

At first glance the Lake Darner looks very similar to the Canada Darner. The main distinguishing characteristics are the distinct dark cross-stripe on the face, the very deeply notched anterior thoracic stripe and a second thoracic stripe that is relatively broad compared to other Aeshna species.

On the average Lake Darners are larger than Canada Darners; this male measured 75 mm in length. In addition the cerci of Aeshna eremita are strongly bent upward and bear prominent bumps on the upper surface, but without a Canada Darner handy to compare these features to the differences were not obvious in the field.

A female Lake Darner, at 72 mm almost as long as the male encountered on September 15th. The field marks are right on the money and identical to those of the male, with a notched (the notch being nearly semi-circular) first thoracic stripe and wide second thoracic stripe ...

... a central line on S2 joining the band on S1, and fused blue spots on S10 (the male deviated on this feature, his were touching, but just barely).

A closeup of the face depicting the cross-stripe.

The terminal appendages (cerci) are rounded at their tips and similar to those of the female Canada Darner. Again, note the fused blue spots on S10.

Details of the genital plate and styli, however, these features aren't useful for separating this darner from other related species (at any rate, they are not mentioned in field guides).

The Lake Darners encountered thus far have been unbelievably tame. The female had captured an insect and, looking for a place to sit and eat it in peace, tried perching on my face twice. A male (perhaps attracted to the female?) stopped to perch in the tall grass within arm's reach as the female was being photographed.

Saturday, September 13, 2014

A Stinkhorn is Born

Theoretically, in the best of all possible worlds a stinkhorn can expand from its immature "egg" stage to full size within thirty minutes. It actually takes several days to produce the nascent fruitbodies (primordia), but once formed, the fungus can bulk up rapidly by taking in water.

The following series of photos illustrating the growth of a Ravenel's Stinkhorn (Phallus ravenellii) spans about seven hours, maybe not fast enough to win any medals in the Fungal Olympiad 100 mm dash, but still a respectable rate of growth.

10:09 AM

10:52 AM

11:30 AM ... soon enough there were flies were checking out the sticky – and despite its obnoxious odor – sugary goo, which also contains the spores.

12:02 PM

12:37 PM

1:45 PM

2:54 PM

3:21 PM

4:59 PM

There was already an older stinkhorn to growing to the right of the "newborn"; the pair of fetid fungi made their presence known at a distance of a good three meters and no doubt insectile senses could detect the stinkhorn's odorous advertisment from a much greater distance. A carpenter ant and two species of flies paid a visit, and upon departure the insects took tiny samples of the spore mass with them, sowing the genes of the phallic fungi far and wide.

A few other fungi were present on the lawn, such as these Xylaria polymorpha, more commonly called Dead Man's Fingers, and they do indeed resemble four fingers – and a thumb – poking out of the ground.

This cluster of Bird's-Nest Fungi has seen better days and is too old to identify as to species. The "eggs" (periodoles) – each containing thousands of spores – that usually occupy the bottoms of the cups or nests (peridia) are long gone, leaving only their impressions in the bottoms of the cups. Like the stinkhorns, Bird's-Nest Fungi deviate from the usual fungal scheme of relying on the wind for spore dispersal. The "eggs" are ejected when a raindrop hits the "nest"; each egg has a sticky string (funiculus) that latches on to sticks, leaves and other woodland floor litter.

Should you happen to be a nematode worm, fear this fungus! Rather featureless and nondescript, it not only makes up for an unremarkable appearance with a tongue-twisting not so ho-hum handle – Hohenbuehelia angustata – it is also a predator, or more accurately, nematophagous.