Wikipedia
The dragonhunter or black clubtail (Hagenius brevistylus), sometimes called the black dragon, is a clubtail dragonfly of the eastern United States and southeastern Canada.
It is much larger than any other North American clubtail, at , with black and yellow markings and green eyes. Males can be distinguished at a distance by their habit of curling their abdomens under while flying, forming a sideways J shape.
The dragonhunter is the only member of genus Hagenius. Its closest relatives are Asian dragonflies of genus Sieboldius. Together the two genera form the subfamily Hageniinae.
The nymph is unusual, with a very flat, wide body. It is slow-moving and lives among bark and leaf litter at the edges of streams, where its dark color provides camouflage.
The adult feeds on large insects, including darner and clubtail dragonflies, sometimes ambushing them from above. It also takes monarch butterflies, eating the thorax and abdomen first to avoid the greatest concentration of cardenolide toxins.