Friday, July 31, 2009

A Few Photos of some Common Damselflies

Most of the damselflies and dragonflies in this blog were identified with the help of the Field Guide to The Dragonflies and Damselflies of Algonquin Provincial Park and the Surrounding Area. This book is a must have reference for the serious naturalist. It covers the Odonata apt to be found in southern Ontario and the illustrations and species accounts are excellent.

The first group of pictures are Pond Damselflies, family (Coenagrionidae).

Violet Dancer (Argia fumipennis violacea), males and female. It's impossible to mistake the males for any other local species.

Powdered Dancer (Argia moesta), male

Stream Bluet (Enallagma exsulans), male, and a mating pair

Skimming Bluet (Enallagma geminatum), males and females

A couple of shots of a male Tule Bluet (Enallagma carunculatum) ...

... and a female Tule Bluet

Tule Bluets mating, in the second photo the pair are just disengaging from the "wheel" or "heart" position.

... and a male Familiar Bluet (Enallagma civile)

The ubiquitous Eastern Forktail (Ischnura verticalis) ... male, immature female, mature female and a mating pair

Fragile Forktail (Ischnura posita), male

A male Slender Spreadwing (Lestes rectangularis); the long, thin abdomen and lack of pruinosity on the last segments are diagnostic. This damselfly is a member of the family Lestidae, the Spread-wing damselflies, which typically hold their wings at about 45° to their body rather than folded together in the manner of pond damsels.

Without a clear photo or study of the male's claspers I stuck my neck out and originally misidentified the following specimen as a Northern Spreadwing (Lestes disjunctus).

The male above is an older specimen with a considerable amount of pruinosity hiding any identifying marks. Moreover, the final arbiter of damselfly species are the male's claspers or female's mesostigmal plates and/or the structure of the ovipositor. It seemed like a good idea to go back and take a closer look. The photo below is another male spreadwing (yes, I'm assuming the same species as above on the basis of appearance but I think it's reasonable to do so). Closeups of this damselfly's claspers are depicted in the succeeding two images. Note how the bottom claspers are very thin; this suggests a Swamp Spreadwing (Lestes vigilax), as per the Field Guide to The Dragonflies and Damselflies of Algonquin Provincial Park and the Surrounding Area. And if I zoom in on the upper claspers, the teeth match the drawings shown in the book for this species.

It seemed like an even better idea to follow correct scientific procedure, capture a specimen, and examine the claspers in more detail in the field. I think the damselfly below is young Swamp Spreadwing male: the colors on the thorax and abdomen are visible and match those in the color drawing in the field guide. More importantly, note the claspers ... I took closeups from several different angles. The upper and lower claspers are the same as on the spreadwings in the images above and as depicted in the book. So despite the fact that the two damselflies look quite different, I can only conclude they are the same species.

The next three photos depict a female (note the ovipositor) Spotted Spreadwing (Lestes congener). This time it's safer to go by general appearances, this is the only spreadwing species with two spots on the side of the thorax.

Three views of a male Spotted Spreadwing (Lestes congener). This damselfly had a few preferred perches on the shoreline grasses and despite its relatively small size (about 35 mm) it was surprisingly aggressive with regard to defending its turf. It took on all comers, not only damselflies of other species larger than itself but even intercepting and chasing a White-faced Meadowhawk that had the temerity to approach too closely.

Dorsal and ventral views of the Spotted Spreadwing's claspers.

Picture-winged Fly (Delphinia picta)

The attractive pattern on the wings combined with an ant-like shape and a rather bizarre proboscis gives this fly a distinctive appearance. Despite its resemblance to a rather large fruit fly, the larvae feed on decaying vegetation.

Wednesday, July 29, 2009

What happened here?

I found this fly covered by a white fluff with its wings in an unnatural position (and quite dead, needless to say) on the underside of a tomato leaf. When I zoomed in on the photos the substance appeared to be a type of mold. Mold is close ... a search of the Internet revealed that the culprit is a fungus ... Entomophthora muscae.