During a biodiversity survey in the forest of central Guyana, an adult male of the damselfly Hetaerina caja dominula Hagen in Selys was found parasitized by a tachinid larva. This constitutes the first record of a parasitoid on an adult odonate, and of an odonate as host of a tachinid larva. CO1 DNA sequencing of the larva placed it closest to the tachinid genera Actinodoria Townsend, Euhalidaya Walton, and Cryptomeigenia Brauer & Bergenstamm in the tribe Blondeliini (subfamily Exoristinae). Pictures are provided of the third instar fly larva protruding from the host, of its posterior spiracles, and of the first and second instar cephaloskeletons.