694 JOLRNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XV 



in clamp situations, on wlii<^li the young foliage first appears, or else 

 they must live during this time on some species other than teak, hut 

 personally I have not found the larvae feeding in this interval. 

 RELATIONS TO THE FOREST. 



58. The economic importance of these insects consists in the enormous 

 damage done hy them to the teak forests, throughout India and Burma. 

 Every year tho larvae of both species may be found, in or near the teak 

 forests, from June to November and in many places from April to Nov- 

 ember. The number of generations passed through in the year is large, 

 and in favourable localities amounts to as many as seven, any one, 

 or all, of which may contain a sufficient number of individuals to 

 entirely defoliate the teak forests in which they occur, and every year 

 one or several more or less complete defoliations, extending over areas 

 of various extent, and caused by one or other of these pests, or by 

 both together, is reported from some part of India or Burma. These 

 widely-spread, continually recurring, wholesale defoliations result in an 

 enormous loss of annual wood increment in the teak forests, and must, 

 to some extent, affect the vitality' of the trees and their power of pro- 

 ducing seed. The trees which have been completely defoliated put out 

 another flush of young leaves, and it is probable that the continual stop- 

 pages in growth caused by these defoliations, followed by flushes of 

 fresh leaves and renewed growth, produce several narrow rings of wood 

 in the year. 



The occurrence of zones of very narrow rings in teakwocd has 

 long been known to be a fact, and various explanations have been given 

 from time to time. In l'JOl I suggested* tho attacks of these insect 

 pests as a possible explanation, which, however, still remains to be 

 proved. 



59. In the dry forests, to which these notes refer, teak areas which 

 have been absolutely defoliated by one generation of the insects are not 

 attacked by the larvae of the immediately succeeding generation. The 

 reason is that the teak here require at least a month to renew their 

 foliage after defoliation, and all moths which appear after tho defolia- 

 tion has been completed, finding no green leaves on which to lay their 

 eggs, leave the defoliated forests and fly to other areas where the trees 

 are still in leaf and lay their eggs there. 



* Vide Indian Forester for August 1901.— " Irregularity in the Growth of Teak." 



