572 



Coccus viridis, Pseudococcus croionis, Eucalymnatus {Lecaniuni) per- 

 foratus and Icerya sp. Aphids, which are more mobile than scales, are 

 scarcely ever protected in this manner, the only instances observed 

 being with Oregma hranthi, Thoracophis fici and other sluggish species. 

 As the galleries apparently pro^^de shelter against smi and rain they 

 serve the ants also, but the latter do not use them for breeding 

 purposes so long as the scales are present. Although D. bifuberculatus 

 cannot be said intentionally to protect scales against their enemies, 

 the practical result of its attendance is to ward them off. It certainly 

 does not attack the Ichneumonid or Coccinellid enemies of C. viridis, 

 nor those that attack P. crotonis, though its presence disturbs them. 

 A note on the favourable influence of D. hitnhercidatus on the scales 

 visited by it [see this Revievj, Ser. A, v, p. 274] closes this section on 

 the relations between this ant and Aphids and Coccids. Other insects, 

 such as various Membracids [Ehhul varius, Walk., Gargara sp., etc.), 

 Psyllids and Aleurodids {AJenrodes eugeniae, Mask., etc.) are visited 

 by D. bifuberculatus in its quest for honey-dew. The larvae of Gerydus 

 boisduvali and other Lycaenids feeding on Aphids and Coccids are 

 visited for the same purpose. 



The natural enemies of D. bitubercidatus include the Tachinid fly, 

 Befigalia latro, de Meij., and the bug, Ptihcerus ochraceus. The former 

 is unimportant, and the latter is a general enemy of the ant. 

 D. bituberculotus does not interfere with other colonies of its own 

 species so long as food is plentiful, but a shortage leads to bitter 

 combats, so that sufiicient space between the colonies must be allowed 

 for when introducing the ant into a plantation. Towards other species 

 D. bituberculatus is even more hostile under the above circumstances 

 and its numbers often enable it to triumph over PJagiohpis longipes 

 (gramang ant) and species of Cremastogcister, Pheidologeton and 

 Mov.om.orium. 



A detailed account is given of the experiments made to determine 

 the exact relation of D. bituberculatus towards Helopeltis, and these 

 have established its value in protecting cacao trees against the latter, 

 M'hich also appears to be prevented from ovipositing on them. This 

 is due to disturbance by the ant and by the white cacao scale, 

 Pseiidococcus crotonis, tended by it. Cacao is also protected to a 

 considerable extent, though not completely, against its other great 

 pest in Java, the cacao moth, Acrocercops cramerella. Regarding the 

 influence of D. bituberculotus on P. crotonis the following conclusions 

 are reached : The mortality of the scale is greatly reduced ; its 

 dev^elopment is somewhat accelerated ; its progeny is considerably 

 increased ; and parasitation is hindered. The presence of D. bituber- 

 culatus is therefore distinctly beneficial, which is not the case with all 

 other ants [see this Revieiv, Ser. A, v, p. 274]. Although complete 

 symbiosis cannot be said to exist between P. crotonis and 

 I). bituberculMvs, the relation between them is very marked. Especially 

 iw cacao plantations, it may be said that while the absence of 

 D. bituberculatus entails that of P. crotonis, the converse also obtains. 



All the above statements and observations relate to cacao 

 plantations. D. bituberculatus was formerly rather abundant in the 

 plantations of Liberian coffee in Central Java, but at present it is not 

 particularly common, probably because the coffee now grown {Cojfea 

 robusta) is not shaded to the same extent. D. bituberculatus is mostly 



