Odonata: Synthemistidae
Choristhemis flavoterminata
The sight of the tiny fly on the tail of this Yellow-tipped Tigertail tempted me to corrupt a poem I read many years ago:
Dragonflies have little flies
Upon their backs to bite 'em
And little flies have lesser flies
and so ad infinitum.
(With apologies to Augustus De Morgan, 1806-1871).
Given the size of the Yellow-tipped Tigertail dragonfly, the fly on its abdomen must be barely 1mm long.