Thursday, February 14, 2013

Here there be dragons (and damsels)...

Hundreds of years ago, much of the world was not mapped.  Most people did not know what existed in the world beyond their horizon.  Maps often had large blank spaces, often with fanciful monsters including dragons drawn in the blank spaces. There is one real globe from the 1500s with the Latin phrase "HC SVNT DRACONES" which means "here are dragons" along the coast of Asia.

Our maps and globes no longer have large blank spaces.  The entire world has been mapped.  There are no longer spaces that are shown with dragons and other monsters, but we do not need to go to the ends of the Earth to see dragons. 

There are dragons around us...

Dragonflies! And their close relatives Damselflies.

While they look similar there are differences between dragonflies and damselflies that make them easy to separate.

(First, let me say that I am horrible at identifying dragonflies and damselflies.  There are hundreds of species, many of which look very alike.  Also, the males and females of many species look completely different.  So it is entirely possible that I have made mistakes in identifying the species below.)

A dragonfly

The easiest way to tell dragonflies from damselflies is to look at is the position of their wings.  Most dragonflies like this one hold their wings perpendicular to their bodies when they rest.

Widow Skimmer

This Widow Skimmer (Libellula luctuosa) is also holding its wings perpendicular to its body.  If you look close you can see another thing that helps to identify dragonflies.  Their eyes are so large that they meet in the middle of the head and cover most of the head.

A close-up of the Widow Skimmer

Ebony Jewelwing - a damselfly
 Damselflies while related to dragonflies are different.  They have skinnier bodies than dragonflies.  They are weaker flier than dragonflies.  Finally, when they rest they hold their wings parallel to their bodies like this Ebony Jewelwing (Calopteryx maculata).
Northern Bluet
 This Northern Bluet (Enallagma annexum) also is holding its wings parallel to its body.

Close-up of the Northern Bluet
A close-up of the Northern Bluet shows that damselflies also have much smaller eyes than dragonflies that do not cover the majority of their head and do not meet in the middle.

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