These conspicuous ants are most often encountered individually or as small groups of 2 or 3 foragers on the surface of the ground any time of the day or night.  Because of their long legs and thin bodies, they superficially resemble spiders.  This is especially true when they are disturbed, as they extend their legs, raise their gasters, and run quickly to escape danger.  This has led to their being given the common name "spider ants."

Nests are found in soil or in dead wood, either standing or on the ground, and are often at the base of trees.  Colony sizes average a few hundred workers and a single queen.  In all but two species, the queen is wingless and worker-like, differing from workers only in being slightly larger and with an enlarged mesosoma.  In the remaining two species, the queens are fully winged, as they are in most other ants.

When a large source of food is found, workers of Leptomyrmex will return to their nest and recruit additional workers to help utilise the newly found resource.  They also use workers as "living storage vessels".  These special workers, called repletes, accept liquids from returning foragers who transfer their liquid foods to these selected workers.  These special workers continue to accept liquids until their gasters become greatly enlarged and extended.  When enlarged, repletes cannot escape the nest and remain inside suspended from the ceiling.  They can retain these fluids for extended periods and dispense it on demand when food is in short supply.