1921] Wheeler: Some Social Beetles 83 



We can picture to ourselves the fierce battles which rage 

 in the petioles between the beetles and the Solenopsis workers, 

 probably mostly at night, for the Solenopsis is a nocturnal spec- 

 ies, and the precarious life of the beetles in parts of the jungle 

 where the ant is abundant. The beetles must live, in fact, like 

 the ancient Greeks, always in danger of invasion from the war- 

 like hords of barbarians. Yet even in quiet recesses of the 

 jungle, where the Solenopsis may happen to be rare or absent, 

 the attachment of the Coccidotrophus colonies to the Tachigalia 

 is sure to be severed as the plant grows and the workers of the 

 colonies started in one or more of the petioles by dealated queens 

 of Azteca or Pseudomyrma have become sufficiently numerous to 

 take possession of every petiolar cavity and patrol the whole sur- 

 face of the plant. Perhaps some of the inquiline ants may occa- 

 sionally kill or oust the beetles, but as these ants merely occupy 

 a petiole here or there on the young trees, they cannot be regarded 

 as very serious enemies. Many of them, too, are small, timid 

 ants, which probably have their own battles to fight with the 

 insidious Solenopsis and are destined to be supplanted, like 

 the beetles, by the obligate Pseudomyrmas and Aztecas. 



During the struggles between the beetles on the one hand and 

 the Solenopsis, Pseudomyrmas, and Aztecas on the other, 

 the poor coccids evidently play somewhat the same defenceless 

 role as the cattle in a country overrun by contending armies — 

 they merely change masters and are either eaten, or carried off 

 or permitted to remain and produce honey-dew for the victors. 

 But before any such change of masters occurs they are often 

 decimated or even exterminated by three enemies of their own, 

 which may be briefly described seriatim. 



In a few of the beetle colonies I have seen a number of 

 larvae of a very small Coccinellid beetle, described by Schwarz 

 and Barber as Scymnus xantholeucus (Zoologica III, No. 6). 

 These larvae when full-grown resemble the larger coccids so 

 closely in size, form and color and are covered with such a similar 

 layer of snow-white wax, that I frequently overlooked them in my 

 living colonies and detected their presence only in the preserved 

 material after my return to the United States. They move slowly 

 about among the beetles and their larvse and devour the coccids. 

 I am inclined to believe that by the time they are ready to pupate. 



