Want your bodyguards to stick around? Give them lodging. Some plants seem to do just that in the form of tiny pockets and hair tufts on the undersides of leaves, offering the shelter necessary to house a population of plant-protecting bugs, report UC Davis researchers. By simulating these naturally occurring shelters, known as "leaf domatia," on cotton plants, the researchers reduced the populations of cotton-eating spider mites and boosted cotton yield by 30 percent. These results, offering the first experimental evidence that plants and certain bugs both benefit from the presence of domatia, are reported in the June 5 issue of the journal Nature. "We think that predatory insects and mites use domatia both for protection from their enemies and for improved microclimatic conditions," said Anurag Agrawal, a UC Davis doctoral candidate, who conducted the study with entomology professor Richard Karban. The researchers hope that domatia from wild cotton varieties might be introduced to commercial cotton through traditional breeding or genetic engineering. They suspect that domatia also might be helpful in controlling spider mite populations, in almonds, walnuts, coffee and avocados.