446 
num box of about 8 cubic inches capacity, and 
had these been available in quantity many more 
insects could have been sent. 
An attempt was made to keep N. savagei 
adults together in a large tin, but this was un- 
successful due to cannibalism even when 8 cubic 
inches were allowed per beetle. 
At first it was thought desirable to provide 
food for the insects during the time they were 
held in Nigeria. Later it was found that they 
fared much better if they were not fed. The 
grubs put into the tins were only partly con- 
sumed, and the rotting remains in the small 
containers evidently created a most unfavorable 
environment. 
Dorylus ( Anomma ) nigricans 111. (Hymenoptera, 
Formicidae, Dorylinae) 
Throughout the search for parasites and pred- 
ators of Oryctes in West Africa it was noted 
that the larvae of the rhinoceros beetles occurred 
in large numbers in standing rotten palm trunks 
but not in fallen logs. In Sierra Leone this situa- 
tion was often observed, but no experiments 
were made to determine why the fallen logs 
were not used by the beetles. It was thought 
that possibly the principal species encountered, 
Oryctes owariensis Beauv., unlike other mem- 
bers of the genus, did not favour such sites. 
On Moor Plantation, Ibadan, Nigeria, an 
experimental grove of coconut palms was found 
to be infested by a fair number of Oryctes 
monoceros Ol. This species was found breeding 
inside the bases of old coconut palm stumps and 
in standing rotten coconut trunks, the products 
of several severe lightning strikes in the grove. 
However, in the numerous rotten trunks which 
had been felled, there were no Oryctes larvae 
nor, for that matter, any larvae of any of the 
numerous species of cetonids and small dynastids 
which usually occur with Oryctes in West Africa. 
There were clear signs that, before the trunks 
had been felled, a considerable amount of breed- 
ing by Oryctes had taken place within them. It 
was also noted that the hollowed interiors of 
these fallen trunks contained much less frass 
than would have been expected. 
Specimens of adult rhinoceros beetles from 
this grove were sent to the British Museum 
(Natural History) with a request that they be 
PACIFIC SCIENCE, Vol. XVII, October 1963 
compared with specimens of Oryctes monoceros 
from East Africa. This was done, and the Ibadan 
species was found to be identical with the East 
African 0. monoceros . 
To determine whether the fallen trunks were 
suitable as breeding sites, four sections were 
selected and set upright. After these had been 
in position for about 3 weeks, they were split 
open. Seven adult beetles of 0 . monoceros and 
14 eggs were collected from them. 
Five sections of the fallen trunks were care- 
fully split lengthwise, and new hollows were 
either carved out by hand or the existing hollows 
were utilized. These prepared sections were 
stocked with Oryctes larvae, and frass was 
packed into the hollows around them. The two 
halves were then brought together and fastened 
in place with bands of wire. Some sections were 
left lying on the ground, others were raised 
slightly at one end. In addition to the logs, a 
sawdust pile was established and stocked with 
larvae of O. boas F. and a few O. owariensis . 
For all of these trials only third-instar larvae 
were available. 
The following events took place: 
1. 15 November 1959. One log was entered, 
and the larvae were eaten by a small greyish rat. 
2. 30 November 1959. All the logs were en- 
tered, the frass was removed, and the larvae were 
eaten by a swarm of "driver” ants, Dorylus 
( Anomma ) nigricans. 
3. 14 December 1959. The logs, having been 
restocked with Oryctes larvae, were again en- 
tered, the frass was removed, and the larvae 
were eaten by a very large swarm of "driver” 
ants, Dorylus ( Anomma ) nigricans. The saw- 
dust pile was also entered by the ants and about 
one-third of the grubs was eaten. 
4. 10 January I960. Additional logs were 
added on 3, 4 January and a small section of 
log which could be moved about with ease was 
prepared. This was placed in the dry bed of a 
stream, about 50 m distant, where "driver” ants 
had been observed. On the evening of 10 Janu- 
ary the ants invaded this log and also entered all 
the other logs in the experimental area. One 
of these logs was constructed so that the larvae 
were in a central frass-packed hollow which had 
no openings at either end. The only means of 
access to this hollow were the holes left in the 
