Thursday, November 25, 2010

An Extraordinary Transfiguration

The emergence of an adult dragonfly from it's larval exoskeleton is one of the most remarkable events in the natural world. Within a short span of time the insect's body is transformed from a squat, cryptically colored aquatic form to a gaudy, streamlined aerial configuration. Thanks to Pauline Campbell for sharing her striking series of images documenting this metamorphosis. The photos were taken at Sand Lake, near Elgin, Ontario.

Dragonflies and damselflies go through incomplete metamorphosis, with their life cycle consisting of only three stages, the egg, the larva or nymph (or more properly, since the larva is aquatic, a naiad or water nymph), and the adult or imago. There's no dormant pupal stage between larva and adult as with butterflies, wasps, beetles and flies.

The first image should actually be last. It's the cast-off larval exoskeleton or exuviae; note the split in the thorax where the dragonfly has exited. However, this picture will serve to illustrate the dragonfly naiad. An insect's exoskeleton is rigid, and in order to be able to grow to this size the naiad has already undergone several molts. Each stage between molts is called an instar.

When it's time to undergo its final molt the naiad instinctively leaves its watery home and crawls to a nearby stone, stick or stem along the shoreline to begin the amazing transition to maturity.

Free at last! The newly emerged adult, called a teneral, pumps haemolymph (insect circulatory fluid) through its body, unfurling the crumpled, stubby wings and lengthening the abdomen. Needless to say, in this state the dragonfly is completely defenceless and vulnerable to predators.

The wings are now fully deployed. This dragonfly is a obviously clubtail, a member of the family Gomphidae, but the colors at this stage are so pallid that it's difficult to identify the species on this basis. Judging by the wide leaf-like profile of the exuviae and comparing it to this Dragonhunter naiad at Discover Life, and looking at this teneral Dragonhunter at BugGuide.Net, I'm going to hazard a guess that Pauline's dragonfly is probably a male Dragonhunter (Hagenius brevistylus).

Here's a link to more Discover Life images of Gomphid naiads.

Although the dragonfly's body and wings are still soft and delicate it's ready to take flight to the relative safety of the shoreline vegetation. In a few days the exoskeleton will harden and assume its adult coloration, and the fully mature insect will be ready to mate and reproduce, perpetuating a cycle of life that extends back 300 million years in time.

Thursday, October 7, 2010

A Myrmecological View of Nature

It's always kind of neat to be able to see the commonplace things we take for granted from a different perspective, so it's back to Laurie Campbell's digital microscope. In keeping with the title we'll start with some images of Lasius neoniger. This little brown ant's crater mounds are a familiar sight on lawns and in sidewalk cracks during the summer months. The objects on the end of the toothpick are the eggs...

... this is the grub-like larva ...

... and the pupa, note how it has the profile of an adult.

The pupa is generally encased in a protective cocoon. I have no idea why the pupa in the image above is exposed as it is.

This is the adult, a sterile female worker.

The next group of images are a tandem pair of bluets, Enallagma sp. Many of these small damselflies are so similarly patterned and colored that they cannot be reliably identified in the field, and an examination of the male's cerci and female's mesostigmal plates is necessary to determine the species. In the following two views, the male's cerci conform to the diagrams in my field guides for a Tule Bluet (Enallagma carunculatum).

While I had the damselfly in hand I took the advantage of the opportunity to get a picture of the unique odonate labium. In naiads this part of the jaws is hinged and extensible, and can shoot out with lightning speed to capture passing prey with the needle sharp tips. (Vestiges of the larval labium can be seen in the images of the Canada Darner exuviae).

Females of many Enallagma species can be tan (like this one), olive, or blue. The mesostigmal plates are a bit difficult to make out, but they too agree with the drawings for Enallagma carunculatum in my reference books. The head and prothorax have been removed in the second image.

A few years ago I was watering my house plants and noticed what looked like a small tick about 2 mm long moving around in the potting soil. Actually, this is a pseudoscorpion, Chelifer cancroides, not something one sees every day. These tiny arachnids don't possess a stinging tail like a true scorpion; their venom glands are contained in their claws.

Pseudoscorpions prey on mites, clothes moth and carpet beetle larvae, and other small arthropods. For more information about these seldom encountered arachnids follow this link to a Photographic key to the Pseudoscorpions of Canada and the adjacent USA.

A couple of closeups of two local centipede species: Lithobius forficatus, the common Brown Centipede often encountered under stones, and Scutigera coleoptrata, the House Centipede which frequently enters older houses. A centipede's venom glands are contained not in its jaws, but the first pair of modified front legs called forcipules, visible just under the heads.

Moths and butterflies belong to the order Lepidoptera, which means "scale wing". In some species the patterns created by the tiny scales are only visible in ultraviolet by others of their kind. These are the scales on the hind wing of a Blinded Sphinx (Paonias excaecatus) ...

... a Twin-spotted Sphinx (Smerinthus jamaicensis) ...

... and an Underwing Moth (Catocala sp.)

The hind leg and wing of a Leaf-footed Bug, a Western Conifer Seed Bug (Leptoglossus occidentalis).

Details of the head, legs and wing of an as yet unidentified gnat; possibly Family Sciaridae, a Dark-winged Fungus Gnat

This spider is a female Furrow Orbweaver (Larinioides, probably sclopetarius).

A closeup dorsal view of the carapace ...

... and a front view. The microscope's depth of field is very narrow making it difficult to focus, but there's enough detail in the image to make out the eyes. The arrangement of a spider's eight eyes are one of the criteria used to determine species.

A ventral view of the cephalothorax. I was hoping to get a picture of the chelicerae but the spider's naturally dark coloring makes it difficult to light this area with an LED side light.

A dorsal shot of the beautifully patterned abdomen.

Ventral views of the cephalothorax and abdomen. The focus in the area where the legs are attached to the cephalothorax is satisfactory and the epigynum is visible, but I was also hoping to capture an image of the lung slits. Unfortunately this was another body part that was troublesome to illuminate. Although somewhat out of focus the spinnerets can be seen at the end of the abdomen in the second picture.

Despite its tiny size, half a millimeter at most, this pupa is my most unusual photo of this year. The closest thing that resembles it is the pupa of a Minute Tree-fungus Beetle, of the family Ciidae (or maybe, as the author in the link to BugGuide.Net wrote "... it could have been a miniature penguin ...").

The pupa seemed to be quite aware of its environment, including my presence, and would rock back and forth about its point of attachment to the grape leaf if disturbed. The following two clips are a shoo-in for the most boring videos of the year ...

Monday, October 4, 2010

Mycological Mug Shots

On October 2nd I had the privilege of attending a fall nature walk sponsored by the Tweed and District Horticultural Society. Many thanks to Donna Fano for her time and guidance in identifying the many fascinating species of fungi found along the trail near Downey's Rapids (a few of the mushrooms below I've identified on my own, if there are any errors, they are mine).

In addition to George Barron's Mushrooms of Ontario and Eastern Canada, Donna also introduced the group to another must have book for the budding mycologist, the Field Guide to North American Mushrooms, published by the National Audubon Society.

First, a look at some bracket fungi. These closely packed shelves of small fungi fruiting on hardwood are called Turkey Tail (Trametes versicolor). The average length of the backets is about 5 cm.

Some views of the hoof-like Tinder Polypore (Fomes fomentarius) growing on a dead birch. These specimens were about 10 cm to 12 cm wide.

About the same width as the Tinder Polypore above and also making itself at home on the fallen birch was an aptly named Birch Polypore (Piptoporus betulinus).

Appearances can be deceiving. At first I took these white 5 cm to 8 cm long formations on this hardwood log to be a species of polypore. Not so ... a look at the underside reveals that these are actually representatives of yet another group of fungi, the Tooth Fungi. I think this might be Steccherinum sp.

Moving on to some gill fungi ... a group of Honey Mushrooms (Armillaria spp.). This complex consists of several closely related species that may require a microscope to distinguish between them, so I'm not going to go farther than the genus level with this one. The caps on these mushrooms were about 5 cm to 8 cm in width.

This mushroom looks like it's been sampled by the local wildlife. Based on what's remaining of the 5 cm wide leftovers I'm going to hazard a guess and call this a Funnel Clitocybe (Clitocybe gibba).

With caps approximately 3 cm to 5 cm wide, brightening up the forest floor is a group of Cinnamon Cort (Cortinarius cinnamomeus)...

... and a vibrantly colored Hygrocybe sp. (width about 5 cm)

Although discolored and faded with age enough of its original reddish hue remains to make this Rosy Russula (Russula sanguinea) stand out among the dead leaves. The width of the cap is about 10 cm.

A common species at this locale, due to their large size (a good 15 cm at their maximum width) Milk Mushrooms (Lactarius piperatus) are also easy to spot despite being half buried under pine needles.

Another common fungus in this area, often found growing on decaying tree stumps and logs, is the Deer Mushroom (Pluteus atricapillus). These mushroom's caps ranged roughly 8 cm to 10 cm in width. (Note: The ID on this may be in error. I've done further research and the gills of Pluteus atricapillus should be free; they are decurrent in the lateral view of the mushroom.)

Most people are familiar with the ubiquitous common puffall but these Pestle Puffballs (Calvatia excipuliformis) were new to me. The rounded end is close to 5 cm in diameter. The second photo includes a complementary Nursery Web Spider, Pisaurina sp.

An older Pestle Puffball, lacking the studded surface.

Smaller and less often noticed than their larger cousins, the jelly fungi are an interesting and colorful group. The following three images depict a Leafy Jelly Fungus (Tremella foliacea). The lengths varied from a few centimeters to about 8 cm or 10 cm.

Witch's Butter (Tremella mesenterica) can be confused with ...

... the superficially similar Orange Jelly (Dacrymyces palmatus). Both of these cheerfully colored fungi measure up to roughly 5 cm in length.

There are two different species of fungi in the following image. The tarry looking stuff is Black Witch's Butter (Exidia glandulosa); the little red cups, the largest being perhaps one centimeter in diameter, are Eyelash Fungus (Scutellinia scutellata). Which brings us to the next group of fungi ... the Sac Fungi, but before moving on, why "Eyelash" Fungus? There isn't enough detail in the photo but when viewed in the field using a hand lens very fine black hairs only .04 mm thick are visible around the perimeter of the cups.

At first glance Dead Man's Fingers (Xylaria polymorpha) doesn't obviously appear to be a sac fungus. Hmmm ... spiders, Witch's Butter and Dead Man's Fingers, and the colors yellow, orange and black ... seems like we have a Hallowe'en theme going here.

Despite their aspect the black and brown domed shapes on this log, roughly 2 cm to 3 cm in diameter, are also sac fungi ... King Alfred's Cakes (Daldinia concentrica).

Tiny, with caps only a few millimeters in diameter, a large grouping of Blue-Stain Fungus (Chlorociboria aeruginascens) decorate a decaying log. These colorful little sac fungi, with cups no more than ½ cm in width, actually have short stems that aren't visible in the photo.

The less gaudy but larger Peziza sp. (2 cm to 3 cm wide cups)

While the "focus" of this walk was fun and fungi there were plenty of other interesting things to be found in the debris on the woodland floor, for example, this Wolf Spider. Probably Trochosa sp., this spider is a big girl at least 15 mm in length, perhaps a bit more.

Something small and green moving among the brown of the dead leaves caught my eye ... an Assassin Bug nymph, Zelus luridus.