88 Zoologica: N. Y. Zoological Society [III ; 3 



the pointed ends of the cavity. Sixty-four of the beetle colonies 

 had larvas and were in what I have called the second and third 

 stages. In nearly every case coccids were seen. Eighty-nine of 

 the colonies were either moribund or extinct. Solenopsis altinodis 

 workers either living or dead, were present, sometimes in con- 

 siderable numbers, in 35 of these petioles, and 10 of them still con- 

 tained large coccids that had been shut oif by webs and were being 

 devoured or had been already devoured by Diadiplosis larvae. In 

 one petiole two of the flies had emerged. In 6 of these petioles 

 the Solenopsis workers had destroyed the beetles and their larvae 

 and were still running about. When I tore away the webs 

 covering the Diadiplosis larvae the ants at once seized and killed 

 them. The webs serve, therefore, not only to protect the Itoni- 

 dids from the beetles and their larvae, but also from the Solenop- 

 sis. 



C. EUNAUSIBIUS WHEELERI SCHWARZ AND BARBER. 



This beetle, though superficially very similar to Coccido- 

 trophus socialis, can be easily distinguished in all its postembry- 

 onic stages. The adult beetle (Plate III, fig. 1, Plate VI, figs. 6 

 to 10) is distinctly smaller, measuring only 3-3.5 mm., perman- 

 ently of a red color like the immature Coccidotrophus and there- 

 fore never deepening into the dark chestnut color of the latter. 

 The antennal clubs are larger and broader and much more dis- 

 tinctly marked off from the more proximal joints, the eyes are 

 much larger, the anterior border of the front is much less 

 deeply emarginate, the femora are less incrassated and the pos- 

 terior pair has a small tooth on the flexor side. The surface of 

 the body is smoother, the punctation being less pronounced. The 

 larva is more slender, with the head and dorsal surface distinctly 

 gray, owing to a deposition of fine pigment granules in the integu- 

 ment. The pupa can be at once recognized by the presence of 

 four large, equidistant tubercles on each of the parallel lateral 

 borders of the pronotum (Fig. 8a, Plate IX, fig. 23) . For many 

 of the less obvious differences between the various instars of 

 the two beetles the reader may be referred to the excellent des- 

 criptions and figures of Schwarz and Barber (Zoologica III, No. 

 6) and Buving (Zoologica III, No. 7). 



