depressed?

The dragonflies that frequent one of the small ponds in ‘La Cité’ go under the name of libellula depressa, or depressed dragonfly.   This year because of the bad weather the females took longer to arrive.  This is good news for the males because more or less as soon as they have mated, they die.  So they got a few extra weeks of flying around until the females arrived.

The blue males hang around the pond and stake their territory, waiting for the smaller yellow coloured female to arrive.  The sound of the male’s flight is very quiet and low in pitch (around the note E on the first stave below the bass clef) and you can only just about hear them when they swoop past.  The female is even quieter.  However, when the two of them mate they do so in flight joining together at both ends (forming a sort of ring) and with both insects flying in unison and colliding wings there is a short twenty second burst of noise before they separate.

This is immediately followed by the female laying her eggs in the pond, hovering above the water and slowing her wing speed down so that she dips into the water and then increasing the wing speed to fly to another part of the pond to dip again.  This succession of audible glissandi is accompanied by the swooping sound of the male dragonfly as he takes guard, and then the show is over: they separate and the pond is quiet again.