162 



roots, and perhaps applying a poison which would in all probability 

 lose its noxious properties after a few hours exposure. 



The nest itself was about two feet in diameter, and constructed 

 round a concealed stump, which had been buried by the earth removed 

 from the drain. 



This main nest was tracked down by following the burrows which 

 always ramify in many directions from attacked Rubber trees. The 

 burrows on flat alluvial land are situated from 1-2 feet below the 

 surface ; they are coated with a thin layer of red substance, are con- 

 structed horizontally, fairly broad and about i inch high, thus forming 

 a passage into which a thick paper knife or a microscope slide could 

 be easily inserted. 



Within these burrows soldiers and workers are often present, and 

 when near a large nest young will usually be found. Occasionally 

 large open spaces are met with, but these are never lenticular in shape 

 such as are formed by several other species. Such spaces are con- 

 structed in the same general plan as the burrows but extend over a 

 greater portion of ground ; the distance between floor and roof is about 

 i inch. 



Ramifying from the spaces are burrows which usually present 

 marked differences in size, those leading to subsidiary nests being the 

 larger ones, the smaller terminating in small dead stumps. Thus if 

 tracking these burrows the smaller ones should be left alone as being of 

 little importance and the larger ones followed which in most cases lead 

 to subsidiary nests. 



These are always, as far as my own investigations go, constructed 

 around or inside old stumps, buried trees, or within fallen trees on the 

 surface of the ground. The buried stumps and trees are often rotten 

 but T. gestroi has no aversion to trees in this condition. The 

 subsidiary nests often contain thousands of individuals and from the 

 former thre issue many burrows one or more of which may encircle 

 rubber trees. 



When this happens the encircled tree is often entirely unaffected 

 by the presence of the ants in their enclosed tunnel, which ultimately 

 connects with other nests. 



That some young rubber trees are attacked and others left alone 

 appears to me to be attributable to the lack or presence of food other 

 than living wood. 



Indications and Method of Attack of Teemes Gesteoi. 



In most insect diseases affecting cultivated plants there occur 

 evidences of the presence of the pest even is the earliest stages, the 

 disease being treated accordingly, thus preventing or at least minimiz- 

 ing the chance of its spreading or becoming serious. 



With Gestroi attack on rubber trees such evidences are often 

 entirely absent until the damage done is beyond redemption. In such 

 cases the tree is either blown down or falls, when its hollow trunk 

 shows that it has been attacked by Gestroi. In the majority of 

 instances trees which are attacked from below in this manner or 

 impossible to cure since one cannot detect that they are in any way 

 unhealthy owing to the absolute lack of any external signs of disease 



