December, '21] 



ESSIG: ARGENTINE ANT 



507 



beetles, lace wings and other allied predators. Besides such protection 

 to the mealy bugs and other coccids, the ants carry them from plant to 

 plant and sees to it that new colonies are constantly being formed until 

 all of the shrubber}^ in an ant-infested district is well supplied with the 

 plant destroying pests. 



A very interesting method of protecting mealy bugs is at present 

 being observed in a greenhouse in Berkeley. As is common in the 

 vicinity, mealy bugs of several species, including the citrus mealy bug, 

 Pseudococcus citri (Risso), Baker's m.ealy bug, P. bakeri Essig and the 

 citrophilus mealy bug, P. citrophilus Clausen, are abundant; sometimes 

 associated upon the same plant and often upon different hosts. But the 

 Argentine Ant is abundant everywhere giving diligent attention to all. 

 The particular greenhouse in question is given over to the culture of 

 the Cape Jasmine, Gardenia sp., all of the plants of which are infested 

 with the citrus mealy bug. The coccids are to be found only in the forks 



Fig. 13. Shelters constructed l)y Argentine ants. 



of the branches near the tips of the plants and in some of the leaf axils 

 singly or in small compact colonies. In the majority of cases the colonies 

 are surrounded by very delicate earthen enclosures as shown in the 

 accompanying illustration. These enclosures are usually oval or nearly 

 spherical in shape and vary from a half to a full inch in diameter. The 

 walls are exceedingly thin and delicate, being composed of fine particles 



