Dorylus
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The army ant genus Dorylus, also known as driver ants or safari ants or siafu, are found primarily in central and east Africa, though the range extends to tropical Asia. There are some 70 species presently recognized, though another 60 names are applied at the rank of subspecies.
Unlike the New World members of the Ecitoninae, they do form anthills, although these are temporary (a few days up to three months). Each colony can contain over 20 million individuals. As in their New World counterparts, there is a soldier class among the workers, which is larger, with a very large head and pincer-like mandibles. They are capable of stinging, but very rarely do so, relying instead on their powerful shearing jaws. Seasonally, when food supplies become short, they leave the hill and form marching columns which are considered a menace to people, though they can be easily avoided; it is for those unable to move, or when the columns pass through homes, that there is the greatest risk. There have been reported cases of people - usually the young, infirm, or otherwise debilitated who could not escape - being killed and eventually consumed by them, often dying of asphyxiation. Their presence is, conversely, beneficial to certain human communities, such as the Maasai, as they perform a pest prevention service in farming communities, consuming the majority of other crop-pests, from insects to large rats.
The characteristic long columns of ants will fiercely defend against anything that encounters them. Columns are arranged with the smaller ants being flanked by the larger soldier ants. These automatically take up positions as sentries, and set a perimeter corridor in which the smaller ants can run safely, though they can only travel about 20 meters in an hour (net). . Their bite is severely painful, each soldier leaving two puncture wounds when removed. Removal is difficult, however, as their jaws are extremely strong, and one can pull a soldier ant in two without it releasing its hold. Large numbers of ants can kill small or immobilized animals and eat the flesh. A large part of their diet is earthworms. All Dorylus species are blind, though they, like most varieties of ants, communicate primarily through pheromones.
In mating season alates (winged queens and drones) are formed. The drones are larger than the soldiers and the queens are much larger. They mate on the wing, and the queens go off to establish new colonies. As in most ants, workers and soldiers are sterile (or non-reproducing) females.
Male driver ants, sometimes known as "sausage flies" (a term also applied to males of New World ecitonines) due to their bloated, sausage-like abdomens, are the largest known ants, and were originally believed to be members of a different species. Males leave the colony soon after hatching, but are drawn to the scent trail left by a column of siafu once it reaches sexual maturity. When a colony of driver ants encounters a male, they tear its wings off and carry it back to the nest to be mated with the queen.
Such is the strength of the ant's jaws, in East Africa they are used as natural, emergency sutures. Maasai moroni, when they suffer a gash in the bush, will use the soldiers to stitch the wound, by getting the ants to bite on both sides of the gash, then breaking off the body. This seal can hold for days at a time.
[edit] Pictures
- A male "sausage fly", ready to have its wings torn off and carried to a queen for mating
- Swarms of driver ants (note here they are called matabele ants, an uncommon name)
[edit] Selected Species
- D. zimmermanni (Santschi)
- D. kohli (Wasmann),
- D. lamottei (Bernard)
- D. wilverthi (Emery)
- D. nigricans (Illiger)
and others
