571 



nest, Avhich he recorded near Singapore and called the chief nest, has 

 not as yet been observed. As trees with suitable opportunities for 

 nesting are jDreferred by D. bifuberadatus, the planters affix artificial 

 nests of leaves, etc., to the cacao trees requiring protection against 

 Helopeltis. Complete shelter without too great exposure to heat or 

 sunshine are the chief desiderata, while the food-supply must be near 

 at hand. It is for this last reason that the ant colonies are numerous 

 only where sugary plant-exudations and insect-secretions occur. As 

 D. bifuberculahis is a tropical species, its habitat is restricted to definite 

 temperature limits, which in Java extend to an altitude of about 

 4,300 feet, or 2.000 feet above the limit of cacao cultivation. During 

 the greater part of the year the colonies contain — besides eggs, larvae 

 and pupae — only two mature forms, the workers and apterous queens. 

 Their number, and the size of the colony, vary very widely, probably 

 according to the accommodation available. Small colonies of not 

 more than thirty individuals may be found between two leaves in 

 contact, while several dozen are present inartificial nests built of leaves. 

 The queens are sometimes very numerous : in an artificial nest of cacao 

 leaves examined in December 1916 there were 610 queens, or 1 to 

 every 90 [sic] of the 52,000 workers. Oviposition is exclusively confined 

 to these queens, and as each of them lays at least 1,300-1,700 eggs, the 

 need for an abundant food-supply is obvious. During the first months 

 of the east monsoon (late June to early September) the winged sexual 

 individuals appear in large numbers. In a colony examined in July 

 1916 there were 680 alate females, 950 alate males, 620 queens, 19,000 

 workers and a quantity of brood. 



The spread of D. biti(berculatus in cacao plantations is usually due 

 to the migration of individuals owing to the increase in numbers 

 which normally occurs in a colony where one or more queens are 

 present. The death of the queens involves the gradual extinction of 

 the colony, for, although new queens may be reared from brood left 

 by the dead ones, they deposit few or no eggs. If the nesting place 

 becomes too sunny or food becomes scarce, the colony migrates. The 

 ants rarely travel on the ground ; their migrations are easily seen and 

 when they are in the direction of cacao plantations their passage can 

 be facilitated by bridging obstacles \\dth bamboos. 



The food of D. bifubercuhius is, in general, similar to that of most 

 ants. This species is not predaceous, however, and it is not a 

 scavenger, one reason being that it lives on bushes and trees where the 

 dead bodies of insects are not abundant. Its chief food is the honey- 

 dew excreted by Coccids and Aphids. The extra-floral nectaries of 

 many tropical plants, especially of the Leguminosae, are sought for, 

 as also are the resinous exudations on bamboo, etc. Workers have 

 been seen carrying the pollen of Luffa acutangida and the half-ripe 

 seeds of Fleurya interrupta to their nest. 



D. bitubercidatus does not remove any of the three Aphids, Toxoptem 

 aurantii, Boyer, Aphis mcdvae, Koch, and A. medicaginis, Koch, which 

 occur on cultivated plants in Java, nor Coccus (Lecanium) viridis, the 

 scale injuring coffee, nor Psetcdococciis crotonis, Green, common on 

 cacao and other plants. The construction of galleries over scale- 

 colonies is usually carried out when the latter are already more or less 

 protected by reason of their situation and chiefly in the case of the 

 species less given to migration. Such galleries have been seen over 



(C423) c2 



