March 1907.] 



181 



PLANT SANITATION. 



Entomological Notes, 



By E. Ernest Green. 

 {Illustrated.) 



A species of 'White Ant' (Catotermes militaris, Desneaux) that attacks 

 and hollows out the stems of living tea bushes has been known for some years. It 

 occurs sporadically in most of the tea districts, independently of elevation. Its life 

 history has hitherto been a complete mystery, no definite nest or abnormally 

 developed breeding females having been observed. Recent investigations in the 

 Lindula district have now enabled me to solve the puzzle. On the estate in question 

 the pest has been known for some years, but no attempt to eradicate it was made 

 until last year. Ic has consequently spread considerably. In some instances whole 

 patches of tea trees have had to be eradicated, Usually, some two or three trees 

 only are affected at one spot. Examination of a number of affected trees showed 

 that the main stem and roots, together with the larger branches, are completely 

 hollowed out, the stem being frequently merely a hollow shell (see fig 1). In spite 

 of this extensive damage the bushes continue to flush well and show no external 

 signs of injury (see fig 2). Only the heart wood is devoured, the sap wood remaining 

 intact and carrying on the functions of the plant. The devoured tissues are 

 replaced by earthy matter into which adventitious roots are thrown out— apparently 

 from the inner walls— and evidently obtain much nourishment from the earthy 

 matter. In digging out the infested trees no signs of extension of the galleries were 

 observed, and no insects were found in the excavated soil. It appears from this that 

 each colony is self-contained in the individual tree, and extends its depredations only 

 when that tree is fully occupied. On splitting open the infested stems and branches, 

 insects in all stages could be found, but no eggs. There were larvae (fig 3)— quite small 

 up to fully grown, full grown workers (fig 4) and soldiers (fig 5), and a few wingless 

 adults (fig <j) of the same size as the workers, but distinguished by their uniform 

 reddish colour and more chitinous integument. The larva} are translucent white ; 

 the workers creamy white with darker cloudy markings on the abdomen ; the soldiers 

 with large reddish heads and prominent falcate mandibles. No eggs were observed ; 

 and nothing resembling a differentiated queen. Nor were there any indications of 

 special brood cells or honey-combed nest. On subsequently dissecting some of the 

 adult insects, their bodies were found to contain well-developed ova— of a very 

 much larger size than those deposited by the specialized queens of other species. I 

 gather, from these observations, that the life history of this species is very distinct 

 from that of the common mound-building termite ; that no specialized breeding 

 queens are produced ; but that the ordinary adults (which are never very numerous 

 iu one colony) are apterous and remain in the nest in which they are raised, and 

 carry on the brood in situ. It is possible that living larvae (instead of eggs,) may be 

 produced, but the evidence on this point is inconclusive. Each colony is therefore 

 self-contained, and the removal and destruction of the tree should destroy the 

 complete colony. The presence of the pest can seldom be recognized until the bush 

 has been pruned, when sections of the galleries are exposed. In recently attacked 

 bushes, only collar pruning can disclose the infection, as the insects apparently effect 

 their entrance through the roots, working up first into the stem and later into the 

 branches. Seeing that infected trees are still able to carry on their functions and to 

 yield (apparently) as much crop as sound trees, it seems a pity to have to eradicate 

 th«m if some means could be employed to destroy the insects in situ and so to prevent 



