USUALLY the females lay clutches under the leaves of ca 40 -80 eggs. The capacity seems to be about 450 eggs in total. These hatch in four days. All of the individuals in this photo are ovipositing females. I saw no males. I have never seen group oviposition before, even in captivity. I have no idea what induced this. Females usually avoid leaves that have eggs. We examined the eggs masses after they had hatched and found very few infertile eggs. The larvae that had been in eggs under others simply ate their way out.
A selection of Dr. Neal Smith's Urania papers:
Smith, Neal G. 1972. Migrations of the day-flying moth Urania in Central and South America. Caribbean Journal of Science 12(2-Jan):45-58.
Smith, Neal Griffith. 1982. Population irruptions and periodic migrations in the day-flying moth, Urania fulgens. Pp: 331-344. in: Jr., A. Stanley Rand and Donald M. Windsor, Egbert G. Leigh (editors). The Ecology of a Tropical Forest Seasonal Rhythms and Long-term Changes. Smithsonian Institution Press, Washington D.C.
Smith, Neal G. 1983. Host plant toxicity and migration in the dayflying moth Urania. Florida Entomologist 66(1):76-85.
Smith, Neal G. 1983. Urania fulgens (Calipato Verde, Green Urania). in: Janzen, D.H. (editor) Costa Rican Natural History, University of Chicago Press, Chicago, 816 pp.
Smith, Neal G. 1990. El Por Qué de la Migración del Lepidoptero Diurno Urania fulgens (Uraniidae: Geometroidea). Pp: 415-432. in: Rand, A. Stanley, Windsor, Donald M. and Leigh, Jr., Egbert Giles (editors), Ecología de un bosque tropical: ciclos estacionales y cambios a largo plazo. Smithsonian Tropical Research Institute, Republic of Panama, Balboa.
Smith, Neal G. 1992. Reproductive Behaviour and Ecology of Urania (Lepidoptera:Uraniidae) Moths and of their Larval Food Plants, Omphalea spp. (Euphorbiaceae). Pp: 576-593. in: Quintero A., Diomedes and Aiello, Annette (editors), Insects of Panama and Mesoamerica - Selected Studies. Oxford University Press, Oxford.