Rhinoceros Beetles in West Africa — Hoyt 
449 
In Nigeria, Coleolaelaps was again found on 
the eggs of Oryctes boas in March, I960, follow- 
ing a few early rains. The Oryctes eggs were 
taken in a large manure heap on the farm of 
the University College, Ibadan. Mite-infested 
eggs were collected and placed for observation 
in covered shallow glass dishes filled with a 
manure and frass mixture. At the same time 
newly laid eggs were obtained from captive 
specimens of Oryctes boas. Mite eggs and im- 
mature and adult mites were transferred from 
the originally infested, field-collected eggs to the 
newly laid eggs and to uninfested, field-collected 
eggs. 
It was noted that Oryctes eggs which had 
mites or mite eggs on them were all slightly 
discoloured and at times showed brownish spots. 
When mite eggs were transferred to non- 
discoloured, field-collected eggs, or to newly laid 
eggs, the mites hatched and in a short time 
made their way throughout the medium to the 
original egg from which they had been trans- 
ferred. Here they gathered and fed on the yolk 
of the now partly collapsed egg. 
The adult Coleolaelaps were never observed 
to feed on either nondiscoloured, field-collected 
eggs or on the newly laid eggs, but they fed 
readily on the discoloured ones and on a non- 
discoloured egg which was punctured with a 
needle. 
None of the discoloured eggs hatched and, 
with the exception of the punctured, nondis- 
coloured egg, both newly laid and field-collected 
ones produced normal larvae. 
No further tests were carried out with Coleo- 
laelaps due to the discovery of other predators 
which appeared to be more promising. 
OTHER MITES ASSOCIATED WITH Oryctes 
In all, some 14 species of mites (Acarina, 
Uropodina, and Canestrinidae ) were found as- 
sociated with the larvae and adults of Oryctes 
in Nigeria. Two of these, a canestriniid and a 
species of the Uropodina, were found commonly 
on the adults of Oryctes monoceros and O. 
owariensis. The canestriniid was found in large 
numbers on the first three abdominal tergites 
beneath the elytra. The uropodinid was taken 
wandering about both on the venter of the 
beetle and under the wing cases. At times both 
species of mites were found heavily infested 
with a fungus resembling closely some of the 
Laboulbeniales. The fungus did not appear to 
harm them, and gravid females were frequently 
observed to produce normal eggs in spite of 
heavy infestations. 
The species of Uropodina found on Oryctes 
was also collected in numbers from the adults 
of Neochryopus savagei. 
SPECIES OF Oryctes ENCOUNTERED 
( Coleoptera, Scarabaeidae, Dynastinae) 
1. Oryctes monoceros Olivier 
Both in Sierra Leone and in Nigeria Oryctes 
monoceros was always found in places where 
there were coconut palms in the immediate vi- 
cinity. On Moor Plantation, Ibadan, this species 
was taken breeding in standing rotten coconut 
trunks and in the bases of coconut stumps. With 
the exception of Moor Plantation, however, 
O. monoceros was rare in all of the places visited. 
2. Oryctes boas Fabricius 
In Sierra Leone Oryctes boas was commonly 
encountered breeding in village compost heaps, 
but in similar sites in Nigeria it was rare. How- 
ever, in Nigeria a large manure pile was found 
at the farm of the University College, Ibadan, 
in which there were thousands of larvae, pupae, 
and adults of this species. In March and early 
April numerous adults and eggs were found in 
this site, but at other times mainly larvae of 
various instars were present. These findings 
seemed to indicate that, while there was some 
overlap of generations, nevertheless there was 
a definite yearly cycle. 
Recently an experimental planting of oil 
palms in Northern Nigeria was reported to be 
rather severely attacked by an Oryctes , and 
specimens extracted from the crowns of these 
palms proved to be O. boas. 
3. Oryctes owariensis Palisot de Beauvois 
Oryctes owariensis is a large species, the well- 
developed adults being larger than the other 
Oryctes species in West Africa and larger than 
0. rhinoceros of Southeast Asia and the Pacific 
