248 INSECTS AND MAN 



skin is tender enough for their mandibles to pierce. In 

 short, it requires the greatest ingenuity to circumvent these 

 little insects; they will even enter refrigerators in search 

 of food. 



In gardens they are no less a pest. Their depredations 

 on the plant tissues are bad enough, in all conscience, but 

 the damage does not stop there, for these insects have an 

 interesting, though disastrous, habit of cultivating countless 

 thousands of scale insects and plant lice, whose excrement 

 furnishes the choicest delicacy with which the ants regale 

 themselves. The result of this protective care is that 

 these insects increase rapidly, with resultant damage to 

 the infested plants. In sugar plantations this habit is 

 specially noxious, because the ant shows great partiality 

 for the excretions of the sugar-cane mealy-bug, Pseudo- 

 coccus calcolarice. So solicitous for the welfare of these 

 noxious insects is the ant, that it builds shelters over their 

 colonies to protect them from storms and enemies, and tends 

 them with unremitting care (Plate XV.). In orange groves 

 this habit of the Argentine ant has resulted in a vast increase 

 of scale insects ; and in fig plantations an injurious scale 

 insect, Pseudococcus citri, is also a protegee of this little 

 insect. Green flies or aphides, too, are always more abundant 

 when the Argentine ant is present, and, in addition to 

 being very unpleasant when they occur on vegetables, they 

 are exceedingly harmful to all kinds of crops. In maize- 

 growing districts, and in cotton fields, aphides have been 

 found to be not only more numerous but more widely 

 distributed when the ants are present, for they, like the 

 scale insects, are carefully nurtured by the ants. The 

 control of scale insects and aphides, therefore, in such 

 districts, practically resolves itself into control of the ants. 

 So much for indirect damage, which in itself is considerable, 

 but is not the only fault that can be laid at the door of 

 Idiomyrmex humilis. Great damage is done by the ants 

 to flowers of all kinds in their search for nectar the fruit 



