The egg-laying habit and the larval hatch process were observed for 2 strains of Aedes albopictus, one from a natural forest and the other from an urban area. The latter females laid eggs easily on a piece of sponge containing tap water. Ninety-five percent of these eggs hatched in tap water within 10 days after being laid. Under the same conditions, the forest strain females laid 80% fewer eggs, which hatched sporadically over several months. However, the forest strain gradually became similar to the urban on during colony maintenance in the laboratory. There was a concomitant increase in the average number of branches of larval seta 1-VII. The evolutionary significance of these phenomena is discussed.
