The Habits of Pheidole (Ceratopheidole) Clydei Gregg (Hymenoptera: Formicidae)

Although the subgenus. Ce’ratopheidole has been recognized or almost three-quarters o a century, virtually nothing is. kno.wn about the habits o. the species included in it. The present study is based upon our nests o Ph. (C.) clydei Gregg. Three o these were situated in Deep Canyon o.n the grounds o the Desert Research Center o. the. University o California. This spectacular and orbidding canyon, cut into. the. eastern slopes o the Santa Rosa Mountains., is about seven miles southeast o. Palm Desert, Caliornia. The ourth nest was at Horse Tanks. in the ’Castle Dome NIountains o _Arizona. It is probable that the. Deep Canyo.n colonies would have gone unnoticed had not a lucky series o events, led to, their discovery. Mr. Charles Musgrove of the, Entomology Division o. the. Citrus Research Station of the University o.f Calitornia showed me a single minor worker which Protessor William Ewart, also of that Division, had taken in Deep Canyon while sweeping tor thrips. Dr. Ewart was good enough to, point out to me bush from which the. minor of clydei had come. Even with this advantage it was some time betore the Deep Canyon nests were tound, or their placement is most unusual. Gregg’s original description o clydei, published in 195o (I) was based upon a. small series of minor workers taken by C. P. Stroud near Carizozo, New Mexico. Since these, were strays it was impossible for Dr. Gregg to give any nesting data for clydei. Later, however, he. published on specimens of both major and minor castes (2) which the Writer had taken trom a nest at Split Mountain in the. Anza Desert State Park, California. Certain teature.s .ot this nest were so peculiar that both Gregg and I hesitated to, accept it as a normal nest of clydei. It was situated in crevices, beneath a weathered lamina of stone which had partially split of{ from the top .of a large boulder that was buried in the sand o the canyon floor. The crevices were tully three eet above the sand and there was not the slightest indication that any of them extended into it. It is now clear that the only abnormal thing about the. Split Mountain colony was that the boulder selected as a nest site was }ar smaller than usual. The three colonies of clydei found in Deep Canyon were in