I've chosen two species of dragonflies for today's spotlight - the Common Darter (Sympetrum striolatum) and Emperor Dragonfly (Anax imperator) - both of which I saw and photographed on the 'Dragonfly Ponds' at RSPB Saltholme today. These are both males. Female Emperors (Empresses, surely) are greenish where the male is blue. Female Common Darters are yellow where the male is reddy-orange, except in older females, which become more greeny coloured.
Common Darter is of the commonest and most widespread of the 36 dragonfly species found in the UK. Emperors used to be restricted to southern and central England and Wales (as shown in the book that I bought in 1997), but are now found as far north as central Scotland. Both can be found in a wide range of different types of waterbodies including ponds, lakes and wet ditches.
Dragonflies, (as well as their cousins the damselflies) have complicated life-cycles and in fact spend most of their lives underwater as flightless larvae known as 'nymphs'. This stage can last as long as five years (although in both these species it is much less) and can involve up to 12 skin moults as the larva grows bigger. Older dragonfly nymphs are among the most fierce and voracious invertebrate predators in the underwater world of ponds and ditches and can take on small fish and tadpoles. The last act of the nymph is to climb up the stem of a convenient plant and undergo its final moult - bursting out of its old skin and emerging as an adult dragonfly. The adults usually only live for a few weeks, during which time they mate and lay eggs (underwater), starting the whole cycle off again.
The two species I've chosen today are one of our largest dragonflies and one of the smallest - Emperors can be nearly 8cm long and Common Darters less than half that. Although the larger species can look alarming (possibly explaining one of the old names - Devil's Darning Needles) they have no sting and are unable to break the skin of a human with their bite (which they would only attempt to do if you held one in your hand).
Hello Colin. I was bitten by a dragonfly last month, the first and only time in my long life. It was a Southern Hawker that I'd liberated from a mist net. I guess you can't expect gratitude from an invertebrate.
ReplyDeleteHi Doug. Did it manage to break the skin? The thing I read said they would try to bite if you had them in the hand but couldn’t break the skin
ReplyDeleteIt was a sharp nip. I was more surprised than injured. You're right, nowhere near strong enough to puncture my skin.
ReplyDeleteOuch!
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