Wednesday, July 31, 2013

Painted Skimmer (Libellula semifasciata)

Last night I was helping a friend sort and identify the odonate images on his HDD when I came across several striking photos of a female Painted Skimmer (Libellula semifasciata). The photo below was taken by Jason King on June 3rd, 2013, about 1.5 km west of Tweed, close to the location where we later discovered a colony of rare Juniper Hairstreaks.

I mistakenly thought the male dragonfly in the next image, taken in 2011, might be a Painted Skimmer, but it's actually an uncommon color variant of a Four-spotted Skimmer – Libellula quadrimaculata praenubila.

In addition to the differences in the wing and abdominal markings, the Painted Skimmer has yellow pterostigmata bordered in black. I would say the specimen in Jason's photo has some yellow in its pterostigmata with strong dark edging. however, they are definitely not completely black as in my Four-spotted Skimmer. Furthermore, according to accounts I've found on the 'net (for example, at Urban Dragon Hunters), L. semifasciata has fewer forewing crossveins than L. quadrimaculata. So barring further evidence to the contrary the dragonfly in Jason's photo is indeed a Painted Skimmer.

I had been forewarned as far back as June 2011 by a reliable authority to keep an eye out for this species in Hastings County, as it had been sighted regularly in Presqu'ile Provincial Park. And I've been recently informed that Libellula semifasciata has been recorded as far north as the Bruce Peninsula (2008 – 09) and Algonquin Park (2011).

It's now late July – two months since Jason encountered the Painted Skimmer. Assuming they emerge early in the season like their cousins, I doubt if they are still flying, and I'll have to wait until next year to acquire my own photos of this attractive dragonfly.

Tuesday, July 30, 2013

Always Look Twice ...

... look a little closer at that dead (or alive!) "leaf" or "twig", look under leaves and flowers, and take the time to turn rocks and logs over. Hold these thoughts on a nature hike, otherwise it's easy to miss out on the really interesting, captivating and ofttimes amusing things going on in the wonderful world of nature.

Sometimes you just have to be lucky enough to be in the right place at the right time. I would have overlooked this tiny green spheroid on a grape leaf had I not caught a female Hummingbird Clearwing in the act of ovipositing.

This closeup of the egg really pushes the limits of the camera's macro.

The stabilimentum of a Lined orbweaver (Mangora gibberosa) – and its handicrafter hiding in the background – easily passed by had the light not caught the silk set against a shaded background. A small spider, the adult female is only about 6 mm in length.

At 3 mm the fancifully named Bowl and Doily Weaver (Frontinella communis) is only half as long. Again, it was the web which gave away the spider's location, otherwise it would have been virtually impossible to spot the tiny arachnid despite its bold, contrasting markings.

What appears at first glance to be a blob of mud stuck to the seed pods of a mustard plant is the handiwork of one of nature's own potters, Eumenes fraternus, more commonly known as – what else? – a Potter Wasp.

A photo taken two days later ... this time the picture includes a complimentary Toadflax Brocade Moth (Calophasia lunula).

Like much out there in the living world the tiny urn (I would guesstimate it's diameter to be about 10 mm) is appealing esthetically, but it's purpose is of course functional, not decorative. The female builds, provisions and seals the nest for its larva; I believe the caterpillar within is a Cankerworm. (By the way, this is a different nest that in the photo above and I found it already broken, I didn't crack it open just to examine the contents.)

No worries about overlooking these boldly colored "bees". The black-and-white wasp on top is Philanthus politus – a Beewolf – and aptly named, as the females sting and paralyze various host bee species in order to provision their larvae. The victim on the bottom with the red abdomen is Sphecodes spp., a member of the Halictid Bee (Sweat Bee) family. Generally Halictid bees collect pollen in the manner of many other bees to feed their young, but Sphecodes is a kleptoparasite, laying its eggs in the nests of other Halictic and Plasterer Bees.

Prickly Ash is so-called for good reason, but these "thorns" are the wrong shape and color. And sometimes one chances across the same thorns on a tree such as Boxelder, where they are definitely out of character. A closer look reveals that these are cleverly disguised Flatid Planthoppers, probably Metcalfa pruinosa. It's fascinating that in order for the deception to succeed the insects must instinctively act as a group and stagger themselves along the twig. A lone planthopper on a twig would hardly look like a thorn, would it?

The long, lacy, almost ethereal fronds of this fern growing in the moist woodland soil at the Vanderwater Conservation Area caught my eye. An expert would no doubt have known what these were, but as a novice to the world of non-flowering plants, one fern looks much like another to me. To facilitate identification I make a practice of studying and photographing the overall aspect of the plants as a group, the fronds, the pinnae, the stipe ...

... and the spore-producing sori on the undersides of the fertile fronds – which also bore small green growths that proved to be pivotal in establishing the identity of the plant. In point of fact, this is a Bulblet Fern (Cystopteris bulbifera) and the little bulblets will eventually drop off and grow into new ferns.

Always look twice indeed – an ant with a ginormous blue-green head scuttling among the debris on the forest floor certainly called for a double take.

Attributing human qualities to an insect may not be good science, but it does seem as if this Katydid nymph is staring back at the camera in a bellicose manner. An insect with attitude – "What're ya'll lookin' at?"

Sunday, July 28, 2013

Stumbling across some Summer 'Shrooms

Fungi make great photographic subjects. They're often colorful and they are always willing to sit still and pose for the camera, the only downside is they often prefer to grow in places where the lighting leaves something to be desired. Above all, they come a an astounding variety of strange and eldritch forms. Given the offbeat shapes assumed by many fungi, their penchant for growing in ill-lit, hidden places and that some bioluminescent species glow in the dark, it's understandable why people in centuries past gave them names like Witch's Butter, Devils Urn, Fairy Ring Fungus and Elfin Saddle.

Fungi are also the foundation upon which other life is built. According to George Barron, in his field guide Mushrooms of Ontario and Eastern Canada (Lone Pine Publishing, 1999), an astonishing 90% of the biomass of a forest floor's soil is fungal. Each tree has thousands of kilometers of symbiotic mycorrhizal fungi associated with its roots that keep the tree supplied with water and nutrients. In fact, I also recall reading somewhere or other that 95% of all plants depend on mycorrhizal fungi for their survival.

The fruitbodies of some 'shroom species are short-lived indeed, and you have to be in the right place at the right time to get a photo. Common and widespread on lawns in the summer, the fruitbodies of Dunce Cap (Conocybe lactea) might last a day.

Gastrocybe lateritia is even more ephemeral ... 9:30 on a July morning and these small mushrooms are already looking rough around the edges.

Many mushrooms change color and form quickly within just a few days, making identification challenging. The photos of this group of Pluteus petasatus were taken two days apart.

Some Xylaria hypoxylon a.k.a Stag's Horn, encountered growing on dead wood in the cedar forest near the Stoco Fen. This is the asexual spore-producing stage of the fungus. Later in the year it will morph to a much different looking sexual phase that produces thick-walled spores and resemble the name it more commonly goes by – Candlesnuff.

Parasola auricoma ... I didn't have to travel far and wide to get these pictures. These small distinctive mushrooms were fruiting the wood chip and bark mulch in the library gardens. The first photo is a younger stage of the mushroom before the caps have fully opened.

A commonly encountered mushroom, Xerula megalospora fruits on lawns, growing from dead wood buried beneath the soil. These two specimens were found in a grassy opening in the forest near the Point.

The stipe often bears a chevron-like pattern, and I was fairly certain I had identified this mushroom correctly based on the other characteristics visible in the photos above. But I has missed a critical identifying feature, something I never thought to look for until I read the species accounts in the Mushrooms of Ontario and Eastern Canada and at MushroomExpert.Com – this species sports a root-like extension up to 8 cm in length.

A few days later whilst out walking at 11:30 PM, I (literally) stumbled across another X. megalospora, so I carefully grabbed the stipe near the ground, pulled firmly upward, and ... wow! The ruler is 40 cm in length and I would guesstimate the length of the "root" to be a good 45 cm.

Last but not least is this crusty, crystalline, cake-like mass about 5 cm in diameter, found growing on a dead stump. Although hard and abrasive to the touch on the outside, the insides were a runny, slimy goo. This is actually a type of slime mold, Mucilago crustacea, and though they are generally included in fungus books and field guides, slime molds also possess the attributes of single-celled animals and scientists aren't sure just how to classify these offbeat organisms.

With the exception of Xylaria hypoxylon and Mucilago crustacea, all of the mushrooms depicted in this post were growing on lawns within a couple of blocks of my place. People often feel that large groups of mushrooms growing amidst the grass on their perfect lawn ruin its appearance and wonder how to get rid of them. Or upon seeing the shelving brackets of a polypore, want to know how to exterminate or remove the fungus from the tree.

The answer is ... forget it. Although the familiar part of a 'shroom that we see – the fruitbody – isn't really a fruit, the analogy still holds. Like an apple or a cherry on a tree, the mushroom we see is only a tiny part of the whole. A fungus mostly consists of a mycelium composed of microscopic threads called hyphae that grow underground in the soil or inside the wood of the tree. Remember that 90% of the forest soil's biomass? At any rate, you can't extricate the mycelium from its substrate any more than you can remove the mold from a piece of bread. So let the mushrooms on the lawn do their thing, and if a tree is at the point where there are brackets growing from it, it's pretty much history ...

Tuesday, July 23, 2013

An Odonate off the Beaten Track

The Slender Bluet (Enallagma traviatum) is not a particularly rare or outstandingly patterned and colored damselfly, what makes this pair of interest is the location where they were encountered and photographed.

The insects in the following four images were not captured so I did not examine the male's cerci or paraprocts, nor the female's mesostigmal plates. The following field marks are as per Page #61, Damselflies of the Northeast by Ed Lam (2004).

– Length is about the same as a Familiar Bluet (about 30 mm) but this damselfy is much less robust
– The color is a powder blue, but a distinctly paler shade than E. civile, E. ebrium, E. carunculatum, and other local bluet species
– The male's abdomen mostly black with blue rings when viewed from above
– Very narrow (virtually non-existent) black shoulder stripes
– Large eyespots connected by an occipital bar
– Prothorax with blue markings (visible in the dorsal view of the male, somewhat visible in the lateral view of the female)
– Top of male's S10 is black
– Narrow black mark on female's dorsal S8

The photos above were taken near the swimming area on the north shore of Stoco Lake in Tweed, Hastings County, Ontario. (Screen capture courtesy of Google Maps.)

However – according to the distribution map for the Slender Bluet in Ed Lam's book, as well as the maps at the MNR's Ontario Odonata Summary Atlas, this species does not range in southern Hastings County. There were some storms with high winds from the west a few days ago, so it's possible these damselflies were blown in from the southwest.

Although I'm fairly certain I've identified the damselflies correctly, I've emailed the images to an expert at the MNR and also uploaded them to BugGuide.Net ... it can't hurt to have some second opinions.

Two days later, on July 25th, I revisited Stoco Lake to do a more thorough survey and see if there any more Slender Bluets present. I observed not one, but two mating pairs – four Slender Bluets – at the exact same tree where the first pair was encountered. And perched on the emergent vegetation about twenty-five meters further south were another five Slender Bluets ... two happy couples busy ensuring their genes were passed on to the next generation, and a solo male.

So it seems that Enallagma traviatum has established a foothold in Stoco Lake. (Have I been overlooking this species, and if so, for how long?) Since I wasn't risking injuring the only known breeding pair I decided to capture two of the insects in order to take some closeup shots. These aren't the greatest macros, but they are good enough to confirm the identity of this damselfly beyond any doubt.

A closeup of the male's head and thorax – note the large eyespots connected by an occipital bar, narrow shoulder stripes and extensive blue markings on the prothorax.

The male's terminal abdominal segments – S10 is black, and the profile of the cerci indicates this is actually sub-species Enallagma traviatum westfalli – Westfall's Slender Bluet. These relatively long appendages are visible in the field.

The female's the head and thorax are similar to the male's, with a lighter line visible along the middorsal carina.

The female's terminal abdominal segments, note the black bar on S8.

July 26th ... yes, it appears that Enallagma traviatum westfalli is here to stay and is by no means an uncommon species in Stoco Lake.

9:55 AM – two males were observed perching on the rushes growing between the culvert and the pavillion. The images of these damselflies weren't worth keeping (out of focus due to strong winds).

10:37 AM – a tandem pair photographed about ten meters to the west of the boat ramp.

10:46 AM – back near the culvert again; two mating pairs of Slender Bluets can be seen in this photo.

A portrait of one of the mating males.

The same pair of damselflies as above ... the insects were so engrossed in mating they were oblivious to external stimuli and it seemed that even a life-threatening event couldn't "bug" them. Indeed, when I captured the pair yesterday to take the closeup shots, I only picked up the male by his wings. In theory the female could have escaped, but she couldn't take flight because her mate continued holding on tight with his claspers. Now that's what I call true love ...

Later in the day I spotted another mating pair near the culvert at 2:12 PM, and a lone female at 2:15 PM. In addition Jason King encountered and photographed a mating pair at the pier, for a total count of thirteen damselflies.

July 27th ... 9:55 AM – one female Slender Bluet sighted between the pavilion and the culvert (photo below). A few minutes later at 10:05 AM I saw another female perching on the shrubbery near the pavilion. It's warm but overcast and windy so there isn't much odonate activity going on. Although the lighting could have been better at least I have an image of a female from a lateral oblique angle nicely showing all of the damselfly's identifying characteristics. Now to get a similar photo of a male.

July 28th ... overcast, windy and on the cool side, but there are plenty of dragonflies and damselflies going about their business among the rushes near the culvert. I spotted two pairs of mating Slender Bluets today around 12:00 noon. Encountering so many mating couples indicates that this species is definitely breeding in the lake.

Any species has to not only reproduce, but do so in large enough numbers to outpace attrition due to – among other life-threatening hazards – predation. One is apt to find three species of spreadings at this site, the Northern Spreadwing (Lestes disjunctus disjunctus), the Swamp Spreadwing (Lestes vigilax) and the Elegant Spreadwing (Lestes inaequalis). And it appears that Enallagma and their other small damselfy cousins are the spreadwing's favoured prey. Today I observed two instances of female Elegant Spreadwings consuming Enallagma males (not Slender Bluets in these particular cases) ...

... and in the image below a female Swamp Spreadwing is eating a teneral female Eastern Forktail. And of course other large odes such as dragonflies aren't fussy about what they eat and will catch and dispatch whatever smaller odonate species they can overpower.

It appears that two of the Slender Bluets weren't victims of predation today, because at 2:22 PM, I encountered another mating pair perching on the rushes near the culvert. Life goes on ...

July 29th ... a mixture of sun and clouds, windy and warm. Some bad news – the town's maintenance crews have mowed the rushes near the culvert where most of the Slender Bluets have been hanging out.

No real harm done – presumably the damselflies were able to evade the mower, and this is a view of the shoreline looking southeast at emergent vegetation between the pavillion and the culvert. The flora is mostly Torrey Three-square Rush mixed with some Flowering Rush, Pickerelweed and White Water Lily.

Since I hadn't checked it out for a few days I decided to re-visit the spot marked on the map where I first encountered the mating Slender Bluets (or perhaps it would be more accurate to say that the bluets encountered me).

I wasn't disappointed ... at 10:20 AM I saw a female perching on a leaf, and not far away on another leaf was a male.

10:24 AM – a satisfactory lateral oblique view of a male Slender Bluet depicting its key identifying marks. It's possible that this might be the same damselfly that I photographed sitting on the leaf a few minutes ago. However, not long after taking this photo I spotted a different male between the "first encounter" tree and the culvert; that makes for a count of three individual Slender Bluets this morning. Note the cerci, relatively long compared to other local bluet species and quite noticable in the field.

Having obtained acceptable images of a male, female and mating pair of Westfall's Slender Bluets, as a rule it would be time to move on to another topic. However, as far as I can ascertain these damselflies aren't supposed to range within about 250 km of Stoco Lake, so I'm going to keep an eye on them for a while ...