Ant damage to banana (Musa sp.) fruits.  Here, a colony long-legged ants (Anoplolepis longipes) in a developing bunch of bananas on the plant was disturbed, and as a defense reaction individuals of the colony ejected formic acid from their abdomens, which contacted the epidermis of the fruits and resulted in the necrosis visible in this photograph.

A nest of ants colonizing a stem of coffee (Coffea arabica).