December, '13] DOANE: RHINOCEROS BEETLE IN SAMOA 441 



in Avater. Such trees were covered with a netting under which a 

 few beetles were placed. A few days later three beetles were found 

 dead in the nets; three had bored into the trees and were apparently- 

 unaffected by the arsenic, but most of the beetles had escaped by 

 tearing holes in the netting. In order that these arsenical sprays 

 might be given a thorough test the crowns were cut from a few trees 

 and the leaves all trimmed off. This part of the tree was very thor- 

 oughly treated, great care being taken that all exposed surfaces 

 received some of the arsenic. They were then placed in a large cage 

 where a few beetles were confined. Sometimes as many as four out 

 of ten beetles would be found dead in the cage the next day, but 

 many of the beetles entered the tree and were apparently unharmed 

 by the presence of the arsenic. No tests were made to determine 

 whether the dead beetles were killed by the arsenic. It was quite 

 common to find some dead beetles in the cage even when the trees 

 that were placed therein were not treated. The results of these 

 experiments are such as we would expect after studying the mouth- 

 parts and feeding habits of the beetle, for little or none of the arsenic 

 would find its way into the stomach unless the leaf or stem fiber was 

 swallowed. 



In an effort to kill the beetles in the trees, without cutting the tree 

 as much as was usually necessary, a little carbon bisulphide was 

 poured into some of the holes after the mass of chewed-up fibres 

 had been removed. The beetles were alwaj^s quickly killed, but, 

 unfortunately, the trees were always badly injured by the liquid 

 and young trees were often killed. 



During the last two years a long series of experiments have been 

 made in an attempt to attract the beetles to various kinds of traps 

 to lay their eggs. The trap very commonly used is made of pieces 

 of rotting logs piled in a neat pile and partly covered with earth. 

 Cacao pods, manure and other decaying vegetable matter adds to 

 the efficiency of the trap. If no other breeding places are convenient 

 the beetles may be attracted to these traps in considerable numbers. 

 At regular intervals, usually every six or eight weeks, these traps are 

 examined and the rotting logs split up and the beetles, larvae and eggs 

 found therein destroyed. If this work is carefully done it is quite 

 effective on well-cleaned plantations, but it is expensive and requires 

 close supervision. If the traps are made of small pieces of well-rotted 

 wood, cacao pods or other decaying vegetable matter mixed with a 

 little earth, the whole mass may be treated successfully with carbon 

 bisulphide by pouring a little of the liquid in holes in various places 

 over the trap. This will kill all of the beetles and larvae except those 



