Abstract: The ant, Polyrhachis dives, is a social insect which lives in a colony often consisting of thousands of individuals. Each colony contains three types. These are the female, the male and the worker. "Females are large, 8—10mm. long. Males are smaller, 7—8mm. long. Workers are of various size, 5.5—7mm. long. Eggs, larvae, pupae and adults can be found in the colonies thrcughout the ycar. Winged females are produced in fall and winter. They nest in trees, shrubs or herbs. Nests are irregular inshape, about 10—39mm. in length and 6—20mm, in width. They feed on insects, honey, honeydew and other sweet glandular secretions of plants. Aphids and coeeids are insects living in symbiosis with them. Some factors that influence their population development were studied. They can play a certain role in the control of Ist-2nd instar larvae of Dendrolimus punctatus in forests.