How to study subterranean army ants: a novel method for locating and monitoring field populations of the South East Asian army ant Dorylus (Dichthadia) laevigatus Smith, 1857 (Formicidae, Dorylinae) with observations on their ecology

A new method employing palm oil as bait was developed for studying the dist ribution and ecology of subterranean army ants. In SE Asia the hypogaeic ar my ant Dorylus laevigatus was found to be very common in both forested and open environments. More than 10 000 workers were found at individual baits. The workers cooperatively dig a three-dimensional tunnel network into the soil. Over a period of 72 days no emigrations of D, laevigatus could be det ected, a first indication of a facultatively stationary way of life in this ant. Encounters with Pheidologeton silenus about food resources were obser ved. In feeding experiments D. laevigatus readily took a variety of arthrop ods and annelids but ignored starch containing vegetables as food. The rare hypogaeic D. (Alaopone) cf. vishnui could be collected for the first time in India and Sri Lanka. Also the epigaeic D. (Anomma) nigricans from Africa were found to be attracted to palm oil. The oil-method thus provides the o pportunity to detect and monitor populations of army ants of the genus Dory lus in tropical and subtropical habitats.