1921] Wheeler: Some Social Beetles 63 



chances upon a coccid, it stops suddenly and seems at once 

 to become more alert or excited, for as soon as its clubbed anten- 

 na; touch the dorsal surface of the insect, their beat, hitherto 

 leisurely and exploratory, becomes greatly accelerated. With 

 each beat, each antenna rapidly describes a minute transverse 

 ellipse on the surface of the coccid, and the beats of the two 

 appendages seem not to be quite synchronous. At the same 

 time the beetle, with a much slower rhythm, rocks its body for- 

 ward and backward by bending its legs, while the mobile arti- 

 culations between the head and prothorax and between the pro- 

 thorax and mesothorax enable it to cover more of the coccid's 

 dorsum and to keep the antennal clubs in contact with its 

 rounded surface. While engaged in this perfomance the beetle 

 resembles an expert pianist moving his hands from side to side 

 over the key-board, or a masseur with his hands in soft gloves, 

 massaging a patient. The beetle undoubtedly distinguishes a 

 large coccid's posterior from its anterior end, since it lavishes 

 most attention on the former. It seems, however, to be quite 

 as interested in the medium-sized or smallest coccids and will 

 spend just as much time in stroking them. The time devoted 

 to the performance in any particular case seems to vary directly 

 with the beetle's appetite or thirst. A beetle may thus spend 

 ten, twenty or even forty or more minutes massaging a single 

 coccid, with occasional short pauses. After a coccid in the 

 proper condition has been stroked in this manner for a few 

 moments it may slowly turn up its wax-penciled posterior seg- 

 ments and discharge from the anal orifice a perfectly limpid 

 droplet of sweet excrement, which the beetle at once greedily 

 swallows. The coccid then flattens down its posterior segments 

 and the beetle resumes its massage. The coccid may thus con- 

 tribute a droplet every few minutes or it may remain inert and 

 unresponsive. An ant confronted with such a situation would 

 take the hint and at once look up another coccid, but the beetle 

 stubbornly keeps on and may work for an hour or more with- 

 out receiving another drink. Usually, however, some of the 

 larvae or one of the other beetles of the colony intervene and the 

 scene may change, as described in a later paragraph. 



That the antennae of the beetle are beautifully adapted for 

 stroking the coccids is apparent at a glance (Plate III, fig. 2, 



