damsel in distress

I am not quite sure what is going on here, but it looks like an aphid has a tiger by its tail. The damselfly was doing its best to dislodge its unwanted passenger by arching its back and rubbing its tail against the blade of grass.

Further research suggests it might be a water mite, various secies of which parasitize dragonflies, damselflies etc (see link for arrenurus genus) ... you live and you learn!