82 Zoologica: N. Y. Zoological Society [HI; 3 



forms till it is quite certain that they have no differentiated type 

 of reproduction." Prof. Thaxter kindly enclosed a drawing of 

 the Coccidotrophns Hyphomycete which is here reproduced as 

 Fig. 12. 



The various organisms just described can, of course, have 

 little or no effect on the health of the beetle colonies. Their 

 decay and eventual extinction is due to ants destroying the 

 beetles and their larvae or to predators or parasites destroymg 

 the coccids on which they depend for an important part of their 

 diet. Colonies in all stages may be invaded by the tiny Solenop- 

 sis altinodis, which I believe to be the most persistent and deadly 

 enemy of the beetles. I have opened petioles containing both 

 beetles and Solenopsis workers, but no beetle larvae or only frag- 

 ments of them, showing that the ants begin their depredations by 

 slaughtering the offspring of the beetles. In such petioles the 

 coccids remain uninjured, and the same is true of the pupae im- 

 mured in their cocoons. Many other petioles reveal conditions 

 from which the last stages in the history of the colony may be 

 inferred. In such petioles only dead beetles and a number of 

 dead Solenopsis are found, indicating that the ants, after destroy- 

 ing all the larvae, attack the beetles and that they, in the ensuing 

 bitter conflict, often defend themselves with their powerful jaws 

 to such good purpose that they succeed in killing many of the 

 ants. But as more Solenopsis are probably continually entering 

 the petioles as auxiliaries the beetles finally succumb and the 

 colony is exterminated, with the exception of such pupae as may 

 be present in their protective cocoons. The beetles emerging 

 from these may, conceivably, after the Solenopsis invasion is 

 over, start a new colony in the same petiole or emigrate to other 

 petioles. If no pupae are present the petiole is sooner or later 

 entered by a pair of young migrant beetles, which pack the dead 

 bodies of the previous occupants, together with the ants they 

 have slain, into the ends of the cavity and establish a new colony. 

 In some of the colonies in the last stages of devastation above 

 described, I failed to find any coccids. They may have been either 

 eaten or carried away by the Solenopsis. Sometimes they remain 

 undisturbed, however, and may, perhaps, be taken over by the 

 beetles emerging from the cocoons or by any pair of young 

 beetles entering the petiole and establishing a new colony. 



