THE ARGENTINE ANT IK RELATION TO CITRUS GROVES. 15 
watched as they simultaneously stroked a mature mealybug on fig. 
Soon the posterior pair of spines moved slowly apart and a fleshy, 
pyramidal organ was extruded, at the tip of which there slowly ap- 
peared a droplet of colorless excretion. This both ants grasped with 
their mandibles, one standing at each side, and held until it slowly 
disappeared down their throats. The excretion was distinctly 
viscous, as shown by the plainly visible indentations made in the 
globule by the two pairs of mandibles, and the slowness with w T hich 
it was swallowed. Ants often have been captured carrying down 
the tree semisolid globules of mealybug excretion. These they car- 
ried in their jaws, as they would carry insects. The excretion of the 
fluted scale also is voluminous and viscid. 
The ants also have been seen to obtain honeydew from a species of 
treehopper (family Membracidae) occurring on goldenrod in the 
Louisiana orange orchards. Only the larvae of this insect (identi- 
fied by the late Mr. Otto Heidemann as Entylia hactriana Germ.) 
w T ere attended by the ants so far as observed. When ready to excrete, 
the tip of the abdomen was elevated and a droplet of translucent 
yellow liquid appeared. This was taken by the ants and carried in 
the jaws like a minute ball of jelly. 
The ants will take the body juices of scales and aphids as readily 
as their excretions, and the aphids often have been cut with a needle 
for the purpose of observing this fact. 
The ants induce excretion in aphids by stroking with the antennae, 
in much the same manner as they do the scale insects. The con- 
sistency of the excretion of aphids varies considerably, that from 
some kinds being thick and jelly like, while from others it is almost 
watery. An aphid occurring on cypress in Louisiana, for example, 
excretes a very thick honeydew which the ants swallow slowly and 
with apparent difficulty. The ants often are seen carrying these 
semisolid globules of honeydew in their jaws to the nest. Usually 
the ant hastily seizes the droplet the instant it appears, the liquid 
being flipped off to a distance if not promptly taken. The black 
scale also appears to throw the excretion to a distance, though not 
observed, as much of the sooty mold collects on the upper surface of 
the leaves which are under the scales. Some of the aphids attended — 
for example, the common orange-infesting species — have well-de- 
veloped abdominal protective siphons, but these organs are absent 
from others. 
RELATIONS WITH INSECTS INJURIOUS TO CITRUS TREES. 
It has been shown that the Argentine ant is rarely directly in- 
jurious to citrus, either through its feeding or its nesting habits. 
Through the one persistent habit of visiting freshly made wounds 
27139°— 18— Bull. 647 2 
