RELATIONS WITH OTHER ARTHROPODA. 65 



During a period of 18 months 48 species of scale insects have been 

 collected in Audubon Park, New Orleans, all of which are attended 

 by the Argentine ant. Many of these species, however, are visited 

 sparingly, and are evidently regarded as sources of food when the 

 more popular species fail to furnish a sufficient amount for the needs 

 of the ants. A few species are particularly favored by the ants, and 

 the trees and plants upon which they occur are always crowded with 

 large numbers of the workers. 



Among these favored species may be mentioned the Magnolia scale 

 (Neolecanium cornwparvum Thro), which is found upon the various 

 magnoHa trees. This scale is very large and unarmored, and the 

 young scales appear in great numbers during February and March. 

 As this is the period during which the ants have the greatest difficulty 

 m securmg sufficient food it naturally follows that they concentrate 

 upon the magnolia trees in immense numbers, and the soil at the 

 bases of the trees is turned mto gigantic ant nests. During June and 

 July this scale is brought under control by the larva of a small black 

 ladybeetle, and the number of ants in the magnoHa trees falls off 

 greatly. By this time, however, an abundance of scale insects and 

 plant lice of many different species can be found everywhere, and the 

 ants do not have to place such dependence upon the magnolia scale. 



Another species which attracts great numbers of workers is the soft 

 scale {Coccus liesperidum L.). This species has been collected upon 

 a variety of plants in Audubon Park, among which may be mentioned 

 the orange, banana, Camellia japonica, coral tree, cocoa tree, rubber 

 trees, myrtle, and maidenhair ferns. This scale can be found in all 

 stages at almost any time of the year, and is always heavily attended 

 by ants. 



Other important scale insects from the Argentine ant's point of 

 view are the sugar-cane mealy-bug {Pseudococcus calceolarise Mask.) , 

 the two barnacle scales {Ceroplastes cirripediformis Comst. and 

 C.Jioridensis Comst.) , and the black scale {Saissetia olese, Bern.) . The 

 last three species are found upon a variety of plants. 



A complete list of the scale insects and aphides which this ant 

 attends would comprise a check list of these species for the entire 

 ant-infested territory. The following list, however, includes the 

 more important species upon various plants and crops which are the 

 most eagerly sought after by the ants. Most of the determhiations 

 have been made at Washington, D. C, through the courtesy of 

 Messrs. E. R. Sasscer, J. G. Sanders, and Theo. Pergande. So far as 

 possible the species most attractive to the ants have been placed 

 nearest the host plants, and they follow m order of preference withm 

 certain limits. 



75508"— Bull. 122—13 5 



