1921] Wheeler: Some Social Beetles 55 



in a cavity diligently cleaning it up for occupancy. Such house- 

 cleaning is necessary both in previously unoccupied and in pre- 

 viously occupied petioles since in the former the particles of fibril- 

 lar or powdery pith, which partially fill the cavity, and in the 

 latter the dead bodies of ants, beetles, etc. must be removed. The 

 entrance opening gnawed in the wall is transversely elliptical 

 and just large enough to admit the slender bodies of the beetles. 

 It is most frequently made in the lateral wall some distance 

 from the narrow ends of the petiolar swelling. The petiole 

 occasionally has several openings, sometimes as many as five to 

 seven. I believe that each of these must be the work of the 

 founders of one of the colonies which have successively occupied 

 the same cavity. In other words, the pair of beetles seems not to 

 utilize the openings of previous occupants for the purpose of 

 entering the petiole but insists on making an opening of it.>^ 

 own, so that the considerable number of orifices occasionally 

 noticed in an old petiole represent the number of colonies of 

 beetles or potential colonies of ants that have from time to time 

 taken up their abode in its cavity. 



The beetles accomplish the removal of the loose pith or the 

 remains of previous tenants by pushing this refuse into the 

 pointed ends of the cavity with their flattened heads, much as a 

 slovenly servant might tidy a room by sweeping things under 

 the furniture or into closets. Smaller particles of pith are 

 sometimes thrown out of the entrance but the decomposed and 

 more or less disarticulated bodies of queen ants and beetles are 

 too voluminous to be disposed of in this manner so that they can 

 only be packed away compactly into the ends of the cavity. This 

 behavior brings the insects into contact with the outermost layer 

 of pith still adhering to the ligneous walls of the cavity and the 

 strips of nutritive parenchyma laden with amber-colored sub- 

 stance. (Plate IV, fig. 1, Plate III, fig. 5). That this tissue 

 actually constitutes the food of the beetles is proved not only 

 by finding it in their intestines but also by actually observing 

 their feeding activities. Very soon, however, young coccids 

 begin to enter the petit)le through the opening made by the 

 beetles and take up their positions on the walls of the cavity and 

 preferably along these very strips of nutritive tissue which, as 

 the beetles feed, become gradually deepened into grooves. The 



