1 6 



or lite cycles in the year. I have said that the insect lays about 

 20 eggs and therefore one female beetle may produce in the year a 

 progeny of 200,000, on the supposition that only five generations 

 are passed through and that only half the eggs are females (the 

 latter however, are usually in excess of males). If there is a 6th 

 generation the number of females incre ses to 2,000,000. 



Taking only 50 per cent of the 5th generation beetles as matur- 

 ing and laying eggs, we still have 100,000 insects as the progeny 

 of the one mother beetle in the spring. This great prolificness 

 easily explains why bamboos suffer so greatly from the shot-borers 

 attacks. 



Towards the end of April of this year Mr. Williams, the Superin- 

 tendent of the Telegraph Workshop, at Calcutta, informed me that 

 bamboos which he was converting into field telegraph posts for use 

 in frontier expeditions and elsewhere were being attacked and 

 riddled by insects. The specimens he sent me 1 identified as the 

 common bamboo boring insect [Dinodermus minutus^ Lesne). As 

 the question of the preservation of bamboos against this insect had 

 been engaging my attention for some time, I immediately paid a 

 visit to the workshops and examined the bamboos. I found that 

 they were being experimentally treated in the following manner 

 before being fitted up as telegraph posts :— 



(1) Five days soaking in river water: 



(2) Five days soaking in a solution of copper sulphate, after 



which they were dried in a covered shed for several days; 

 and then 



(3) Soaked for 24 hours in common Rangoon oil. This latter 



has the effect of darkening the bamboos and the smell of 

 the oil remains in them for some considerable time, al- 

 though not so offensively as to prevent their being made 

 use of. The treatment lasted about 14 days upon the ex- 

 piration of which period the bamboos were at once sent 

 to the workshop to be fitted. Mr. WILLIAMS had reported 

 that within three weeks of this treatment some of the 

 bamboos had been again attacked by the borers. As some 

 9,000 had been through the treatment the ease afforded a 

 good opportunity for experiment. I wished to find out: — j 



(1) How many more generations of the beetle appeared in the 



year. 



(2) Whether the oil treatment was of any use. 



(The experiments, which numbered fifty-five, took place between 

 April 29th and October 30th. Male bamboos i. e. solid bamboos 

 were placed in boxes constructed of tin foil with close fitting tops 

 of wire gauze and treated in various ways with water, coppe| 

 sulplate and Rangoon oil both singly and in combination ) 



The experiments show I think the following: — 



(1) That neither the five days in water nor that followed by a; 



