Subfamily: Paussinae (ants' guest beetles, ants' nest beetles)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthopoda > Mandibulata > Atelocerata > Panhexapoda > Hexapoda > Insecta (insects) > Dicondyla > Pterygota > Metapterygota > Neoptera > Eumetabola > Holometabola > Coleoptera (beetles) > Suborder: Adephaga > Family: Carabidae (ground beetles)

Small to medium sized (4-20mm) beetles, uniformly dark or pale reddish brown in colour. Their most distinguishing features are the broad, flattened antennae. All species live in a myrmecophilous association with ants and these antennae have been reported to be used as handles by ants to drag the beetle around the nest. The beetles secrete a volatile substance from subcutaneous glands that is greedily licked up by the ants, appeasing them and suppressing their usual aggression toward intruders. In exchange, the beetle and larvae feed on either food provided by the ants or the larvae feed on the ant brood.

In more specialised species, the beetle mouthparts are spoon-shaped to readily receive the drops of food from the ants' mouthparts. The more primitive species rely more on brute force and defend themselves with a tough integument (covering) and bombard the attacking ants (or humans) with a gas that contains quinone secreted in special glands. The gas volatilizes explosively releasing a puff of vapour. 

In some species, the adults only leave the nest for reproduction and they probably occur above the ground during the seasonal swarming of ants.