The abdomen is composed of three main parts: the petiole, the postpetiole, and the gastor. There are a total of nine segments in the abdomen, however one has become vistigial or nonexistant in some species, and several are hidden, leaving a total visible count of five or six. Each of the segments are composed of two pieces, the tergites and the sternites. The tergites are the over arching pieces, while the sternites are the under arching pieces. The petiole and the postpetiole are the second and third segments of the abdomen, respectivly. The gastor is the last, bulbous structure of the ant, and has a telescoping construction of seven segments. It is in fact flexible and has a little freedom of move ment.

The base of the abdomen contains a particular organ, called the stidulatory organ, that is comprised of a washboard type of construction on one segment, and a set of very small teeth coming down from the over hanging portion of the segment infront of t hat containing the 'washboard.' The ant is able to produce a very high frequency song with this organ by raking the teeth across the 'washboard', with which she can signal to other ants.

Located at the end of the gastor is the ant's sting and its accompanying sheath. The ant is capable of extending the sting and injecting a poison, generally some mixture of formic acid. It is this sting incojunction with the madibles that is used to ad minister the ant bite. Unlike the sting of a bee, the ant's sting is not barbed and can therefor be retracted to be used again.