In this image, ants appear to be biting one another. There are differing opinions regarding the reasons for the inititation of this behavior, such as trophallaxis or odors. Ants in the same colony engage in trophallaxis when they appear to mouth-to-mouth position. This behavior allows the mixture of chemicals storing in their postpharyngeal glands to achieve consistency among the colony. In other words, ants may attack other ants with different odors. Different odors may be produced by different colonies or due to illness or aging. Are the ants in this image showing trophallaxis or a fight? It is difficult to tell. Perhaps only the ants themselves know.