Saturday, June 11, 2011

Off-Color Odonates

This female Libellula quadrimaculata (a.k.a. Four-spotted Skimmer) was encountered near the intersection of Alexander Street and the Eastern Ontario Trail. The dragonfly was foraging in a field of tall grasses, weeds and wildflowers. A small sand-and-rock bottomed creek and the Moira River are nearby. At first I mistook it for a Painted Skimmer as it flew by, but Libellula semifasciata would be a vagrant in this area.

The black patterning at the end of the abdomen and basal patches on the hindwings are correct for a Four-spotted Skimmer. However, not only are the spots at the nodes are larger and darker than the norm, but the wings are barred near their tips. I don't know what to make of this: is it a normal variation? A sport? Are hybrids between L. quarimaculata and L. semifasciata possible? At any rate, it's certainly different ...

The following day I saw another Four-spotted Skimmer with a dark wash near the nodes and wingtips at the same location, and also emailed a copy of the Four-spotted Skimmer photo to David Bree, who kindly responded: "... it is a dead ringer for a 4-spot. The amount of black at the tip of the abdomen is like a 4-spot and not a Painted as well. I don't think the node spots are bigger than normal. All these markers are much more distinct on young four-spots, they do fade with age ... Some pictures I've seen in field guides actually show this species with that same dusky wash though not quite as distinct as yours."

Another anomalous odonate: a female Dot-tailed Whiteface with a generous amount of amber at its bases of its wings. Now and again I've encountered Leucorrhinia intacta with a bit of color but this really caught my eye as the dragonfly hovered above the grass.