THE ARGENTINE ANT IN RELATION TO CITRUS GROVES. 15 



vatched as they simultaneously stroked a mature mealybug on fig. 

 50on the posterior pair of spines moved slowly apart and a fleshy, 

 >yramidal organ was extruded, at the tip of which there slowly ap- 

 >eared a droplet of colorless excretion. This both ants grasped with 

 heir mandibles, one standing at each side, and held until it slowly 

 lisappeared 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 which 

 t was swallowed. Ants often have been captured carrying down 

 he tree semisolid globules of mealybug excretion. These they car- 

 ded in their jaws, as they would carry insects. The excretion of the 

 luted 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 

 ouisiana orange orchards. Only the larvae of this insect (identi- 

 fied by the late Mr. Otto Heidemann as Entylia bactriana Germ.) 

 were 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 

 Lhe 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- 

 istency 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 



