Rhytidoponera victoriae & Amblyopone ferruginea

The worst enemies of ants are often other ants. Here, a Rhytidoponera victoriae scout (at left) has discovered a Amblyopone ferruginea worker and attempts to wrestle it back to her nest. If successful, she will kill the Amblyopone and feed her to the larvae. Amblyopone is too specialized as an underground predator to be good at general fighting, so is at a disadvantage here. Diamond Creek, Victoria, Australia

Oecophylla smaragdina weaver ants have killed a trap-jaw ant and are cooperating to carry it up a tree branch to their nest. Cape Tribulation, Queensland, Australia

An Argentine ant (Linepithema humile) attacks a much larger fire ant (Solenopsis invicta). Both species co-exist naturally in subtropical South America, but in the southern United States where both have been accidentally introduced, the fire ant has displaced the Argentine ants. Austin, Texas, USA

Tetramorium immigrans

The happenings of the insect world play out mostly unnoticed by people. Here, two colonies of Tetramorium pavement ants battle for territory along the shores of a midwestern reservoir. Clinton Lake State Recreation Area, Illinois, USA

Tetramorium immigrans

Tetramorium pavement ants fight to determine the territorial boundary between two colonies. These fights are a regular feature of the biology of this species, often conspicuously staged on sidewalks and other places where this species occurs. Clinton Lake State Recreation Area, Illinois, USA

Azteca alfari Cecropia ants guard their tree zealously against intruders. Working together, they surround and immobilize their opponents such as this trap-jaw ant by pinning down their appendages. Gamboa, Panama

Podomyrma gratiosa

A large Podomyrma gratiosa tree ant attacks a column of smaller Crematogaster workers that pass too close to her nest. The Crematogaster fight back, and even though the large size and heavy armor of the Podomyrma allow it a one-on-one advantage, the superior numbers of Crematogaster give the smaller ants the edge in this fight. Naracoorte, South Australia

Acromyrmex versicolor & Novomessor cockerelli

Harvester ants (Novomessor cockerelli) tear apart a queen leafcutter ant (Acromyrmex versicolor) they have caught after a leafcutter mating flight. Ants won't often eat members of their own species, but they will happily consume ants of other species. Tucson, Arizona, USA

Nomamyrmex army ants are among the few animals that successfully attack leafcutter ant nests. The leafcutters are not without their defenses. Here two Atta workers attack and kill a Nomamyrmex esenbeckii scout, preventing the army ants from discovering the leafcutter's trail. Gamboa, Panama

Amoimyrmex silvestrii

Leafcutter ants don't normally fight with other types of ants, but they can be brutal towards other leafcutters. Here, a trio of Amoimyrmex workers team up to kill an Atta saltensis leafcutter that has wandered into their territory. Santiago del Estero, Argentina

Azteca alfari Cecropia ants do not tolerate other species on their host tree. When intruders are encountered, the Azteca patrollers work together to pin them down. Interestingly, the offending insects aren't always killed. This Camponotus was simply dragged to the edge of the plant and dropped. Gamboa, Panama

Forelius nigriventris and Solenopsis invicta. A juxtaposition of two very different defensive strategies. The fire ant (at right) brandishes her venom on the tip of her stinger, while the opposing Forelius worker aims hers as a volatile spray. Santiago del Estero, Argentina

Forelius nigriventris attacking a fire ant worker (Solenopsis invicta). Santiago del Estero, Argentina

Her nest breached by attacking Forelius nigriventris (at right), a fire ant adopts typical defensive position: stinger raised and exuding a droplet of volatile venom. Santiago del Estero, Argentina

Forelius nigriventris and Solenopsis invicta. When Forelius gain access to a breach in a fire ant mound, a full-scale ant battle ensues. Here, a fire ant (at left) flicks a droplet of venom towards the Forelius aggressor. Santiago del Estero, Argentina

A harvester ant (Pogonomyrmex desertorum) wanders too close to a nest of little Forelius mccooki ants, who harass the intruder until she leaves. Tucson, Arizona, USA

Crematogaster acrobat ants use their stingers in defense, but they don't pierce the integument of their opponents. Rather, the stinger serves as a brush for smearing defensive chemicals on their adversaries. Here, a worker defends a food bait against an intruding Pheidole. Kibale forest, Uganda

Argentine ants (Linepithema humile), an aggressive pest species introduced by human commerce to California, attack a native Pogonomyrmex harvester ant. Native ants in many places around the world have disappeared in areas invaded by Argentine ants. Davis, California, USA

Argentine ants (Linepithema humile), an aggressive pest species introduced by human commerce to California, attack a native Pogonomyrmex harvester ant. Native ants in many places around the world have disappeared in areas invaded by Argentine ants. Davis, California, USA

Argentine ants (Linepithema humile) fighting. Argentine ants typically form large supercolonies comprising millions of ants and thousands of nests. Within these massive supercolonies fighting is rare, but ants from neighboring supercolonies readily attack each other. Córdoba, Argentina

Linepithema iniquum workers from neighboring colonies fight over access to an orchid plant. Maquipucuna reserve, Pichincha, Ecuador

Myrmecia pilosula jack-jumper ants from neighboring nests, engaged in battle. Tower Hill, Victoria, Australia

Myrmecia pilosula jack-jumper ants from neighboring nests engaged in battle, grabbing each other with their impressive mandibles and attempting to sting their opponent with the tip of the abdomen. Tower Hill, Victoria, Australia

Neivamyrmex californicus army ants are specialist predators of the brood of other ant species. Here worker army ants attack a defending Tetramorium worker as others plunder the Tetramorium brood. California, USA