Brilliant Emerald (forest pond, Stuttgart, Germany). Thanks to <a href="//commons.wikimedia.org/wiki/User:Fice" title="User:Fice">Fice</a> for help with the identification.
<a href="//commons.wikimedia.org/wiki/User:Pjt56" title="User:Pjt56">pjt56</a>--- If you use the picture outside Wikipedia I would appreciate a short e-mail to pjt56@gmx.net
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>