Tuesday, June 21, 2016

Not a Wasp

Eastern Amberwing Dragonfly - female - REK
When I saw this small insect sitting on a sage in our backyard, I assumed it was a wasp with its coloration and twitching wings and abdomen seeming to explore the blossoms.  I took a quick series of pictures before it could fly away.  Only enlarging the pictures later did I discover what a treasure I had captured.

This is an Eastern Amberwing Dragonfly, Perithemis tenera, the second smallest in the US.  Measuring less than an inch long, its size and colorful wings are said to look like nothing else in the region.  The abdomen is narrow at the base (connection to the thorax) and then widens out. Its appearance and movements mimic a wasp, felt to be a defensive advantage.

Male Amberwing - Stan Gilliam CC
The males have orange to golden wings with small black spots.  The females' wings are clear to amber with larger black splotches or bands.  The females' abdomen is thicker, not body shaming as the males seem to go for this look.

Their mating and reproduction has been extensively studied in amazing detail considering how small and quick these dragonflies are.  It is described here at Odonatacentral.
The male "patrols and defends these territories, as potential egg laying sites, where they regularly perch on emergent sticks or twigs. These small territories, less than 5 square m, are only accepted by the male if he is not disturbed and there is no competition from other males. Females appear and are courted by the male. He will fly out to her and lead her back to his prospective oviposition site, hovering with his abdomen turned up. Upon acceptance by the female, signaled by a slower wing beat, the pair perch on a twig and mate, taking 20-30 sec."
Only a few dragonfly species actively mimic wasps.  Unlike most dragonflies, Eastern Amberwings are "perchers," frequently found sitting on flowers while ignoring any pollen or nectar, posing just like wasps.  They will sometimes adjust their body and wings to absorb the least amount of the sun's heat on a sunny day. They prey upon mosquitoes, flies, ants and wasps that crawl over our flowers.  Good hunting, little lady.

The UWM Bug of the Week has more details and is worth a read.  (Now he tells me!)
Also see Odonatacentral.org.

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