Certain species of COCCIDAE that excrete honeydew and are attended by ants or enclosed in their nests are quite prevalent on tea bushes and seed trees in the plains of Assam and West Bengal but those which are not attended by ants are kept under considerable check by the activities of their natural enemies. In Darjeeling, where the natural enemies are fewer, a number of species occur abundantly and are often responsible for serious damage to tea.

From the studies of the relative population of the ant, Crematogaster dohrni Mayr and the Coccid, Saissetia formicarii (Green), occurring on tea bushes it is doubtful if more than a small portion of the food requirement of the vast ant population in the nests which contain sexual forms could be met from the honeydew excreted by the small number of Coccids enclosed therein. The major part of food must, therefore, come from other sources. Insects attacking or visiting the tea bushes and tea seed trees or even those found on the ground appear to constitute the major part of the food of the ants, C. dohrni and Oecophylla smaragdina (F.).

Several factors are responsible for the decrease in the population or disappearance of the Coccids in the absence of attendant ants. In the plains, Eriochiton theae Green, Coccus hesperidum L. and S. formicarii entirely disappear in the absence of attendant ants either due to the activities of their natural enemies or by contamination with honeydew accumulation or both. Parasitism may be slightly higher in ant-free colonies, but no estimation was possible since, in the absence of ants, the Coccids are quickly destroyed by predators.

The ants do not protect the Coccids from Hymenopterous parasites; but their active movements hinder the parasites in their efforts to oviposit, and this leads to a reduction in the rate of parasitisation.

In the presence of the ants, O. smaragdina and Crematogaster dohrni, predators are rare; they are destroyed as are any other insects or any foreign bodies that happen to be near their nests, whether they constitute food or not. The larvae of predators which have a protective covering or which resemble Coccids, if they happen to have gained access to the Coccid colonies, are not attacked by the ants, because they are not recognised as different from the Coceids.

O. smaragdina does not normally transport Coccids, though young nymphs of E. theae and Coccus hesperidum may be aided in their dispersal, but Crematogaster dohrni and Crematogaster sp. are primarily responsible for the dispersal of S. formicarii and this takes place when an occasion arises to remove the Coccid to more favourable sites.

O. smaragdina does not destroy the nymphs and sedentary form of Coccus hesperidum for food, but sedentary forms which are unable to establish themselves on transfer from withered leaves to a new nest are eaten.

With the control of the attendant ants, the honeydew-producing Coccids disappear or at least they become rare. Conversely, where the Coccids are controlled, the ants automatically disappear.