2 BULLETIN 647, U. S. DEPARTMENT OF AGRICULTURE. 
The Argentine ant has been the subject of special study by this 
bureau for several years, more particularly as to its activity as a 
house pest, but also as to its general economy in relation to garden, 
orchard, and field cultures. The facts secured in the investigations x 
prior to 1913 indicated a very important injurious relationship of 
this ant to citrus culture in Louisiana. As a result of this apparent 
condition and in response to numerous complaints of injury to citrus 
trees occasioned directly and indirectly by this ant, a special in- 
vestigation was instituted in 1913 under the supervision of Mr. C. L. 
Marlatt, Assistant Chief of the Bureau of Entomology, to deter- 
mine the exact economic importance of the ant as a citrus pest and 
to devise effective means of preventing damage in citrus orchards. 
GENERAL BELIEF AS TO DAMAGE TO ORANGE TREES. 
It has been recognized generally that a few species of ants may 
injure orchard and other crops either directly, by feeding on plant 
parts, or indirectly, through their symbiotic relations with scale 
insects and aphids. 
The important features of the activities of ants toward certain 
scales and aphids, viz., soliciting " honeydew " excretion from them, 
carrying them about, constructing shelters over them, and combating 
their enemies, were pointed out more than a century ago by Pierre 
Huber, 2 some of whose observations were made upon orange-infesting 
species. Huber, however, makes no mention of injury caused to 
orange trees by these habits. 
Direct injury by ants, so severe as to cause the death of the trees 
in orange, cacao, coffee, and cotton plantations in the TTest Indies, 
is cited by the French historian Robin, 3 contemporaneous with 
Huber. Robin probably referred to leaf-cutting ants, Atta spp., 
several species of which destroy trees in tropical America by de- 
foliation. 
Although the habits of ants in relation to plants and plant pests 
have been studied by many observers since these early writers, ex- 
treme views as to damage to orchard trees by ants, especially through 
the fostering of insect pests, have developed only since the Argentine 
ant became established thoroughly in southern Louisiana. This ant 
made the greatest impression upon people by its unusual abundance 
and aggressiveness, and became the subject of study by many laymen 
as well as entomologists. Interest in ants, especially as orchard 
1 Titus, E. G. Report on the " New Orleans " Ant. U. S. Dept. Agr. Bur. Ent. Bui. 52. 
190*. 
Newell, Wilmon, and Barber, T. C. The Argentine Ant. U. S. Dept. Agr. Bur. Ent. 
Bui. 122, 1913. 
2 Huber, Jean Pierre. Recherches sur les Moeurs des Fourmis Indigenes. Paris. 1810. 
'Robin, C[laude] C. Voyages dans l'lnterieur de la Louisiane . . . 1802-1807, Tome I, 
p. 215. Paris, 1807. 
