Spotting an ant nearly a half-inch long is enough to make you step back and let the creature pass without harassment. Imaging seeing millions of ants this size and larger, cutting wide swaths through the forest. You might not care at that point whether the ants are the army or driver varieties, since both types of ant are large by ant standards and share ferocious appetites and painful hunting techniques. Army and driver ants exhibit many similar characteristics, such as living nomadic lives, but several differences also exist.
Large and Intimidating
As large as they are compared with the ants you typically see creating tiny mounds in the cracks of your sidewalk, army ants (Eciton burchellii) are smaller than driver ants (Dorylus nigricans). These ants hail from different genus classifications, but their behavior is amazingly similar. The main difference in the genus types is the shape of the mandibles -- army ants have long mandibles in the front of their faces, while most driver ants have them spaced out on the sides of their heads. In both species, the queen is the largest ant. Army queens usually run about a half-inch long, while driver queens can reach nearly 2 inches. Army ant workers can be as small as a tenth of an inch, ranging up to nearly queen size. Driver ants, however, run from about an eighth of an inch to a little over an inch.
Strength in Numbers
Both types of ants form huge colonies, much bigger than other ant species. But driver ants take the award for the largest colonies. Their numbers sometimes grow to 22 million individuals. Army ants, on the other hand, usually stay between 100,000 and 2 million ants per colony. Both colonies are nomadic, forming temporary nests for a short period of time, such as three weeks, then traveling daily for two or more weeks. Because the ants can decimate insect populations in an area quickly, this constant movement keeps them from starving while it gives insects a chance to rebound where the ants previously nested.
Overpowering Their Prey
Army ants, especially the smaller ones, have powerful stings for subduing prey, which runs from insects to small mammals and reptiles. Larger workers can sting, but they also have strong mandibles with which they rip off pieces of prey, often starting with the legs and antennae to disable the prey. Driver ants don't usually sting, although they can. Instead, they rely on mandibles to rip apart prey quickly. While one ant wouldn't be effective using only mandibles, driver ants travel in groups of thousands, with hundreds available to swarm over prey at any given moment.
Where They Live
Both species of ant prefer to live in forests, particularly rain forests with abundant prey. They occasionally venture into open land or less wooded areas when necessary. Both nest in trees, under logs or in brush piles, shoring up the exterior by linking their bodies together to form a living shield around the queen and her eggs. However, the ants live on different sides of the world. Army ants live primarily in Central America and South America, while driver ants inhabit areas in Africa.
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