Defense in thrips: forbidding fruitiness of a lactone.

Expulsion of anal fluid from the upturned abdomen was demonstrated to serve a defensive function in the thrips Bagnalliella yuccae. An allomone in the anal exudate was identified as gamma-decalactone, a fruity-smelling compound that repelled potential predators. Chemical defenses may contribute to the ability of thrips to maintain large aggregations.