December, '13] DOANE: RHINOCEROS BEETLE IN SAMOA 439 



through the bristles with which the mouth is surrounded. Examina- 

 tion of the alimentary canal of man}^ beetles failed to show any of 

 the plant fiber. The importance of this will be seen when we come 

 to consider control measures. 



The life history of this insect has not as yet been thoroughly worked 

 out but in Samoa it probably takes it at least a year to complete its 

 development. The eggs, which are laid in batches of ten to thirty, 

 hatch in a very short time and the larvge feed for several weeks, 

 possibly for some months. In Samoa the larvae are found most 

 commonly in old decaying coconut logs or stumps, in places where 

 these occur, but other rotting wood or decaying vegetable matter of 

 any kind seems to furnish an abundance of food. The cacao pods 

 that are often left in piles in the field furnish excellent breeding places. 

 The larvae are not commonly found in the living trees, but, if the 

 croA\Ti is badly injured and contains much decaying matter, they 

 may sometimes occur there. 



One tree about twelve years old that, when standing, appeared to 

 be only moderately injured was cut down and found to contain fifteen 

 beetles, twenty-four larvae, one third to one half grown, three smaller 

 larvae and a few eggs. A few larvae and eggs were also found in other 

 trees so that it is possible that, when the breeding places on the ground 

 are not so readily available, more of the beetles will lay their eggs 

 in the injured trees. 



Unless a special search is made for them the pupae are rarely seen 

 and they are never found in any considerable numbers. Those that 

 are found are usually' in well-formed cells in portions of the log that 

 are a little firmer than that in which the larvae commonly work. 

 Many of the larvae probably enter the ground and pupate some dis- 

 tance below the surface. The pupal stage lasts for about ten days 

 or two weeks. It is very difficult to rear the beetles from pupae that 

 have been taken from their cells. Not only are the pupae very easily 

 injured but they do not seem to be able to live except under the most 

 favorable conditions. After the beetles issue they remain in the logs 

 for a few daj^s, waiting for the body wall to harden. Their flight is 

 slow, heavy and, in the breeding cages at least, not very long sustained. 

 In a cage 8 x 8 x 16 feet the longest flight noted was two and one half 

 minutes. They probably would fly for a much longer time outside. 

 They fly only at night, and sometimes come to lights, but even the 

 brightest lights do not attract them in great enough numbers to be 

 of any value in control work. 



In Samoa many control measures have been tried. In the effort 

 to protect the trees from attack, many substances which were supposed 

 to act as repellants have been used. Our observations and experi- 



