A wedding took place on the beach a couple of properties down from our house this last week and as soon as the deal was being sealed, a particularly large flyby of iridescent green and black moths fluttered by the newly betrothed. An attendant was heard to say whether they had arranged for that to happen, a reasonable query considering the timing. However, what was being witnessed is the migration of Urania fulgens, the Green Page Moth.
This Uraniid moth is reknown for its large scale migrations in Costa Rica. The migration begins in July or August and may last several months though it tends to be staggered every 4 to 8 years. The reason lies in its host plant, Omphalea diandra, a woody vine in the euphorbia family. The leaves provide low amounts of toxic chemicals to which the caterpillar incorporates into its system to discourage predation. However, as foraging intensifies, the plant produces higher concentrations of defense compounds that can subsequently kill the caterpillars. Adults must then move to a new region where the vines leaves haven't recently been exploited by the moth. The exodus takes Urania to the lowlands north of San Carlos and the Caribbean slope of Costa Rica and Panama. The spectacle we are treated to this March is the return to the original breeding area in the forests of the Osa Peninsula.
Of course, none of this means a drop of nectar to the wedding planner who chanced upon a fairy tale wedding including a sky filled with green and black jewels and a sunset kiss.