Calopteryx caducii

Of these, deserving further mention is the Conjoined Demoiselle, which, though duller in colour than most Zygoptera, is remarkable to view in its element, for throughout adulthood it keeps close, and relies upon, the carcass of a sibling. They hatch as yoke-fellows, fused at the tail, and develop so united. But at the very instant the final juvenile carapace falls away, a fierce urge drives the pair to part, with great ensuing strain. As with a wish-bone, the inevitable break is uneven, and the twin with the shorter end perishes, deprived of an essential mass of nerves. This corpse becomes the survivor’s instrument in securing its meat, much as a carved waterfowl aids a hunter of living birds. The Demoiselle lurks hidden in tall grass with its dead relation nearby but in plainer view (Plate F, fig. 8b shows this scene with male subjects), until the corpse is molested by the desired visitor — who then suffers a surprise attack. This singular method perhaps does not seem so curious in the eyes of an insect whose quarry is exclusively the Ridged Micrathena, which could easily make a meal of its hunter.

From: W.J. Good (Rev.), Common Objects of the Country. Routledge & Co., 1858: p. 126.