460 Ridley.—Symbiosis of Ants and Plants. 
ant haunts these Korthalsias, but that any ant whose habits induce it 
to adopt this class of dwelling may do so. 
The primary use of the ochrea is undoubtedly to throw off rain from 
the base of the young bud which it at first covers, and thus it is not in any 
way a modification for the benefit of the ants. The only possible advantage 
that the ants could bring to the plant would be to defend it against the 
attacks of caterpillars or other insects. Now neither in the forests nor 
in the open part of the Gardens are the ochreae always occupied by ants; 
neither are the unprotected plants of K. scaphigera and K. echinometra 
more liable to insect attacks than the protected plants; and, again, the 
species, like K.jiagellifera , which do not possess swollen ochreae are equally 
exempt from insect attacks. 
There are, indeed, but few insects which attack the foliage of palms 
even under cultivation, and even less in a wild state. The commonest 
caterpillar which attacks any palm is Erionota Thrax y one of the skipper 
butterflies. The caterpillar, which is of large size, is of a light sea-green 
colour and powdered all over with a white floury substance. It rolls up the 
leaves of palms and ensconces itself therein, devouring the leaf from within. 
The white powdery dust (wax) protects it from the action of water, but also 
from the attacks of ants. I have unrolled a leaf-tube containing one of 
these caterpillars in the neighbourhood of a nest of the tree ant Oecopliylla 
smaragdina , which is a great destroyer of caterpillars. The ants ran all over 
the caterpillar and attempted to attack it, but were deterred by the white 
powder, and soon left the caterpillar unhurt. 
The ants which frequent Korthalsia are smaller and much less 
ferocious than the Oecophylla , and are much less likely to attack so large 
a caterpillar. 
Furthermore, plants of which the adult leaves are attacked by cater¬ 
pillars are in this country seldom seriously or permanently injured, at least 
in a wild state, where they grow isolated from other plants of the same 
species, as these plants commonly do in the forests. The loss of a few adult 
leaves is quite unimportant to the plant. The matter is different in cases 
where the young leaves when just opening from the bud are attacked 
persistently, as will be seen in the case of the Macarangas. 
Taking the whole facts of the myrmecophily of the Korthalsia 
together, it will be seen that they do not fill the requirements for a true 
symbiosis. The ants are not always present, yet the plant unprotected does 
not suffer from their absence ; more than one species of ant frequents 
the ochrea of the rattan ; there is no special modification which can only be 
accounted for as of use to ants ; there is no clear benefit to the plant from 
the presence of ants at all. 
