The popular image of termites as timber-munching pests needs to be overhauled. In tropical forests, the vast majority of termites do not conform to the stereotype, say researchers at the National History Museum in London. Instead, most termites eat rotting vegetation in the soil and nest underground. They may be as important to the survival of these forests as earthworms are to the health of household gardens. In the last two years, Paul Eggleton and his team have been measuring the biomass and biodiversity of organisms in soils in Cameroon, west Africa. Soil-dwelling termites accounted for more biomass than any other animal group. The total mass of the world's termites may be three times that of its human population. "Until now, nobody was aware of the enormous weight of termites underground," Eggleton says. These subterranean species dig intricate networks of tunnels, shifting the soil and improving its aeration. By consuming rotting vegetation, they also help to recycle nutrients taken from soil by trees and plants.