24 February 2011

Blue Skimmer - Orthetrum caledonicum

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Blue Skimmer - Orthetrum caledonicum

Skimmer dragonflies belong to the Libellulidae family, with Orthetrum caledonicum occurring Australia wide and probably the most common. It can frequently be seen around Esperance on the edge of almost any creek or pondage, or at least the male dragonfly can. The females from my observations only visit to breed and rarely stay long, which may be the result of intense male interest.

Usually several males will take up positions around a waterway, where they spend a fair amount of their time perched on the ground or low vegetation near the waters edge. Other males that cross into these areas are promptly escorted out, so naturally with such strongly guarded territories any visiting female is vigorously pursued. After mating the female may check out the aquatic prospects for her offspring, but will not stay long and move away until she has the need to deposit her eggs.

The females I have observed, fly without the male around the edge of the pool and periodically dip their tail into the water, presumably to drop an egg, again she does not stay long and soon moves away from the water. I would imagine this egg laying activity would be repeated during the day until she decides to go elsewhere. So in order to see the females, you need to be either very lucky by being in the right place at the right time, or copy the male’s example and perch quietly nearby and wait patently.

There is a similar dragonfly also recorded for the Esperance region, but I have not seen it locally. It is the Black-headed Skimmer, Crocothemis nigrifrons and like its name suggests is much darker around the head and synthorax; the abdomen although also powder blue, is a deeper shade. However different wing venation is diagnostic between species, but these cannot be illustrated here as detailed diagrams are required to show variation.