1921] Wheeler: Some Social Beetles 69 



week and the supply of water in the plant tissues has consider- 

 ably diminished, the excretions of the coccids are less frequent 

 and copious, so that the beetles and larvae become more and 

 more thirsty and therefore more desperate and exacting. Thus 

 by the very simple device of keeping the colonies for some time 

 in tubes, it is possible greatly to exaggerate the attentions of 

 the beetles and their larvae to the coccids and to witness certain 

 peculiarities of behavior which are less obvious in recently col- 

 lected colonies. 



When a number of thirsty beetles and larvae surround ? 

 large coccid, all stroking different parts of its dorsal surface 

 and periphery, only the individual that happens to be stationed 

 at its posterior end is able to secure any honey-dew. The beetles 

 and larvae all keep at work, however, till the antennae of two of 

 them happen to meet. Then the larger individual stops stroking 

 for a moment and butts its competitor with the side of its head. If 

 the group is formed by a single beetle and several larvae, the beetle 

 being the stronger, soon pushes any larva with which it may come 

 in contact away, but the latter usually at once returns and re- 

 sumes its stroking till contact with the beetle again occurs and 

 the butting is repeated. When several larvae of different sizes 

 have preempted a coccid, the largest treats the others in the same 

 manner. This behavior is so suggestive of that of a number of 

 pigs eating out of the same trough that one can hardly doubt that 

 something more than a mere reflex is involved in the butting. The 

 larger beetle's or larva's indefatigable perseverance in butting 

 is only equalled by the pertinacity with which the butted indivi- 

 dual keeps returning and resuming its stroking movements. I 

 can illustrate this best by transcribing a few observations from 

 my note-book. 



August 10, a beetle was seen standing over the posterior end 

 of a large coccid and stroking it busily. At short intervals the 

 coccid raised its anal segments and discharged a minute limpid 

 globule of honey-dew, which was at once avidly seized and 

 swallowed by the beetle. During 11 minutes the coccid raised 

 its tail 25 times and the globule could be distinctly seen on 

 most occasions, as the beetle paused suddenly in its manipula- 

 tions and moved its labium and palpi each time a globule was 

 imbibed. Sometimes the beetle would pause for a ' moment. 



