Monday, June 28, 2010

Trying to make sense of Teneral Spreadwings

These immature spreadwings, photographed at the marsh bordering the Eastern Ontario Trail about one kilometer west of town, lack the colors and patterns of adults. Virtually tenerals, they are about the length of an Emerald Spreadwing, about 40 mm, but much less robust. Distinguishing the Northern (or Common) Spreadwing (Lestes disjunctus) and the Sweetflag Spreadwing (Lestes forcipatus) can confound even experts and lacking experience I'm finding it difficult to determine the species. To add to the chaos, although they can usually be differentiated in the field there are teneral and immature Emerald and Slender Spreadwings competing in this same habitat, all within the same few square yards. Pairs of adults will be studied in future to determine if both species are extant in this area.

Although the dorsal colors of the thorax and shoulder stripes don't agree with the illustrations for an adult Northern Spreadwing (Lestes disjunctus), the sides of this immature male are pale yellow. The teeth on the cerci, shape of the paraprocts and narrow profile of the apical hood also look correct for this species.

Lateral view of another male; note the pale yellow sides of the thorax and claspers similar to those of the other male above.

Dorsal view of a third immature male's claspers.

Lateral and ventral views of a fourth male's claspers.

Oblique and lateral view of an immature female, possibly Lestes disjunctus. The sides of this individual are pale yellow. The backs of the heads of both males and females depicted thus far are dark.

The ovipositor looks correct for Lestes disjunctus.

Now things get confusing. Unfortunately I was unable to acquire of photo of the entire damselfly as a view of the postocular area would be helpful. The claspers are different than the three featured above. While the paraprocts appear to be the same the profile of the apical hood looks wider and the teeth on the cerci are subtly different. Is this a normal variation of Lestes disjunctus? An effect of the camera angle and lighting? Or are we looking at the terminal abdominal segments of an immature male Sweetflag Spreadwing (Lestes forcipatus)?

Views of an immature female; the postocular area appears pale. The pattern of the darker areas on the dorsal surface of the abdomen agree with those for Lestes forcipatus (but is this significant in the case of a teneral?).

Detail of the terminal abdominal segments. In the images above it's obvious that the large ovipositor extends well past the end of the abdomen. Although the Emerald Spreadwing has a long ovipositor, it is nowhere near this size in any individuals that I have seen, and the Emerald Spreadwing is much chunkier in appearance in any event. A darker lower rim would be desirable to help nail the identity down, however, the other criteria strongly suggest this is an immature female Sweetflag Spreadwing (Lestes forcipatus).

A teneral male Slender Spreadwing (Lestes rectangularis). In addition to the length of the abdomen this spreadwing can be identified in the field by the pale veins on the outer margins of the wings.

Tuesday, June 22, 2010

The Tadpoles are turning into Tiny Toads

Less than a quarter of an inch long and easily mistaken for an insect or spider, there are hundreds of these little guys currently scampering about on the lakeshore.

To give an idea of scale here's the toadlet sitting in the palm my hand; it's small enough to easily fit on the nail of my pinky finger.

Other tadpoles are turning into tiny Spring Peepers. There is no way to judge size in this image, but this little froglet, encountered in the vegetation bordering the Eastern Ontario Trail, was the same size as the toad above and could fit on my pinky nail with room to spare.

Might as well put these photos of a Green Frog (Rana clamitans) here. This guy is an adult about three inches long, and is sporting his best colors, hoping to attract a girl friend. The dorsolateral ridges (the seams starting behind the eyes and running down the frog's back) set this species apart from the bullfrog.

These Gray Treefrogs (Hyla versicolor) were photographed near the culvert running under the Eastern Ontario Trail just a few feet from where I encountered the Spring Peeper. Gray Treefrogs can vary their color to match the background, and these two were doing a pretty good job of blending in with the leaves of the Virginia Creeper they're sitting on.

A "thumbnail sketch" of the frog on the left ...

... and the frog on the right.

A Gray Treefrog of a dramatically different color. This adult was happily camped out in the reservoir under a potted tomato plant on a second floor balcony. Fully grown frogs are about 5 cm long, twice the size of the little guys depicted above.

In Pursuit of the Perfect Picture ... and People Friendly Butterflies

The Hackberry Emperor (Asterocampa celtis) seems to be uncommon locally, as its name implies the larve feed on hackberry. A beautiful specimen, likely recently emerged and showing no faded colors or wear and tear of the wings.

After patiently pursuing this subject for about half an hour hoping to get a good dorsal view of the wings, the butterfly finally stopped and posed for the camera ... on the cuff of my pants. Maybe it was attracted to the smell of my running shoe?

Yes, it must be my scented shoes. The Red Admiral (Vanessa atalanta) visible in the upper right took flight just before I could snap a picture of it sampling my clog's chemistry. The caterpillars, on the other hand, have different tastes and prefer to feed on plants belonging to the nettle family.

Vibrantly colored and without torn wings or missing parts, the butterfly perched on a nearby rock and sat still long enough for me to take a couple of pictures.

Another Red Admiral checking out the taste my jeans.

Most butterflies of the subfamily Satyrinae, such as the Northern Pearly-Eye (Enodia anthedon), prefer shaded moist woodlands. These insects tend to rest with their wings closed making it hard to obtain a dorsal view, and when sitting motionlessness on bark they are almost invisible.

Another people friendly species! Actually it was a hot humid day and what the insect was attracted to was the chemicals in perspiration on my hand. I often walk through a considerable amount of mud and water in the pursuit of the perfect picture, and the Hackberry Emperor and Red Admiral in the foregoing photos were attracted to my shoes for similar reasons.

A couple more members of the subfamily Satyrinae (a.k.a. Browns): I was unable to get a dorsal view of this Little Wood Satyr (Megisto cymela) but in this case it wasn't necessary to make an identification.

The two large pale rimmed eyespots on the forewings of the Common Wood Nymph (Cercyonis pegala nephele), visible from both above and below, make this butterfly easy to "spot" at a distance.

It can be challenging at best and often impossible to make a positive identification at the species level from a picture and you can never have too many views from different angles. Although the following two butterflies can be distinguished by inspection of their dorsal wing patterns, the undersides of the wings are radically different for a Northern Crescent (Phyciodes cocyta) ...

... and a Harris's Checkerspot (Chlosyne harrisii), making it easier to differentiate the two in the field or from a photo.

You never knows what will cross your path at an unexpected moment and it's impossible to be ready for everything. A faster film speed would have captured more detail of this Silvery Blue (Glaucopsyche lygdamus) courtship.

The orange spots on the ventral sides of the wings, and the tails on the hindwings, are distinctive field marks of the Eastern Tailed-Blue (Everes comyntas) ... if you can see them. Peterson's Field Guide to Eastern Butterflies gives the minimum length as 20 mm but this tiny butterfly appeared to be only half of that.

Two more of our commonly encounterd local "tailed" butterflies, the Gray Hairstreak (Strymon melinus) ...

... and the Banded Hairstreak (Satyrium calanus).

The lakeshore is a good place to hunt for butterflies, where they are attracted to the moisture and bird droppings. But it takes a bit of luck to stumble across one worth photographing and the wings of this Mourning Cloak (Nymphalis antiopa), a bit rough around the edges, reflect the realities of life in the wild.

This Mourning Cloak didn't land on my hand voluntarily because attracted to my scent. It was at the side of the road, stunned by a collision with a car, so I took advantage of an opportunity to take its picture in exchange for a safe place to rest and recuperate.

The Eastern Comma (Polygonia comma) is another "people friendly" insect that has landed on me on several occasions. The silvery comma-shaped mark, the butterfly's namesake, can be seen on the underside of the hindwing. The color and pattern on the ventral sides of the wings combined with their irregular profile is a near perfect imitation of bark, and the butterfly virtually disappears when it perches on a tree trunk.

Mourning Cloaks, Tortoise Shells, Commas and Question Marks overwinter as adults and are the first butterflies encountered in the spring, often when there's still snow on the ground. The black, almost purplish border along the hindwings indicate this is the is the summer form of the insect. This area of the wing is orange in the winter brood .