The two termite species, which originated in separate areas of Asia, spread across the world by hitchhiking in cargo holds. There are only three places in the world where both species have a foothold: Hawaii, Taiwan, and South Florida, but usually the ants' mating seasons don't overlap. In Florida, the Asian subterranean termite mates in February, months before the Formosan. But in both 2013 and 2014 researchers observed both species mating at the same time, producing large broods of hybrid termites. The researchers note in the paper that both years had warm winters in Florida, hinting that climate change could have forced the change in mating season.