64 THE AKGENTINE ANT. 
in great numbers on sugar cane, Johnson grass, willows, and oaks, 
and, in fact, in all places where a number of coccids or plant lice are 
exposed to the weather. 
The stimulation resulting from the attentions of the ants while 
collecting the sweet liquids appears to have the effect of greatly 
encouraging the numerical increase of the aphidids and coccids. 
During the summer of 1910 the junior author reared several genera- 
tions of sugar-cane mealy-bugs on sugar cane planted in large pots. 
One-half of these pots were isolated from the Argentine ants, while 
to the others they were allowed free access. The mealy-bugs grew 
and multiplied in both lots of cane, but there was great difference 
between the thriftiness of the isolated and nonisolated msects. In the 
pots to which the ants had access the mealy-bugs multiplied so freely 
that finally they almost smothered out the sugar cane with their 
cottony egg masses. In the isolated pots, while the mealy-bugs 
increased hi numbers, they were not nearly so numerous or healthy 
looking as in the ant-infested pots. At the end of two months the 
number of mealy-bugs in the ant-infested pots probably exceeded 
the number of mealy-bugs hi the isolated pots to the extent of at 
least five to one. 
That the same conditions exist in the cane fields is shown by the 
number of mealy-bugs which can be found in the fields infested by 
the Argentine ant as compared to their scarcity hi fields not infested 
by the ant. Only one field under the latter conditions has been dis- 
covered as yet, but it has been watched closely for two years. The 
mealy-bugs have never become sufficiently numerous to attract the 
attention of the working hands, and they can be found only with 
considerable difficulty. On the other hand, in the fields where the 
mealy-bugs and ants are associated the former have become so 
numerous that the white cottony egg masses can be easily observed 
from the road while driving through the fields. 
The same thing holds true with scale insects generally. In the 
orange groves invasion by the ants is followed by a rapid increase of 
scale insects, particularly the chaff scale (Parlatoria pergandii Corns t.) 
and various species of Lecanium. So rapidly do these scales increase 
that, unless prompt measures are taken against the ants, the second 
year of infestation shows a severe curtailment of the crop, and the 
fourth or fifth year witnesses the death of many of the trees. The 
rapid decline of orange trees under conditions of heavy ant infestation 
is well illustrated by Plate VI, which shows a tree after exposure to 
attacks of the ants and chaff scales for three seasons. 
The ants constantly attend the citrus white fly (Aleyrodes citri 
K. & H.), and a marked increase in this injurious pest always accom- 
panies ant infestation. 
