They will look, too, at the amount of ice in the ground, and the temperature and the moisture of the soil.

ECONOMIST: Global warming and the permafrost

So in the last year of their 17-year life cycle, when the soil temperature reaches about 64 degrees Fahrenheit, they crawl out of the ground by the billions.

NPR: Roar of the Cicada

The satellite images picked out the right type of afforested land, and topography, which, when combined with other data on soil types, rainfall, and temperature, produced a clear "Loa Loa map" of several African countries, including Burkina Faso, Mali and Niger.

BBC: Danger worms tracked from space