Termites are fussy eaters. A particular piece of wood may be avoided because it is too hard or contains defensive chemicals that the termites can't detoxify. Different termite species also vary in their food requirements, and such selectivity may help to reduce competition, allowing different species to coexist in the same habitat. Even wood size matters — one species may specialize on entire timber-framed buildings, whereas another may have an appetite only for twigs.
Theodore A. Evans and colleagues have tackled the problem of how termites assess wood size (Proc. Natl Acad. Sci. USA 102, 3732–3737; 2005). Worker drywood termites (Cryptotermes domesticus, pictured) are blind and so cannot judge wood size visually and do not survey the wood physically before starting to eat. The researchers considered another possibility. Termites often communicate with vibrational signals — soldiers, for example, may drum their heads against the wood to warn of impending danger — and they are also noisy eaters.
Evans et al. wondered whether termites use vibrations generated during foraging to judge the resonance frequency of the wood, which is related to its size. To test this possibility, they presented hungry worker termites with blocks of wood of different sizes. The workers preferred blocks of a particular size, but this preference could be specifically altered by playing them recordings of termites feeding, or by producing artificially generated vibrations. Remarkably, the vibrational signals also affected reproductive development in the species, suggesting that such signals might play a wider role in termite biology than has been appreciated.