1935] 
Beetles Associated with Ants 
225 
It does feed upon injured Microdon larvae, chewing the 
flesh of wounds and licking the exuding body fluids. It 
has also been observed to attack and put to flight the 
larger staphylinid, Gastrolobium bicolor. Formicarius 
drinks from small pools of water in the artificial nests. In 
drinking, the head is lowered and the fore-legs spread apart ; 
the water is pushed into the mouth by the maxillae and la- 
bium, while the mandibles are held widely agape and partly 
immersed in the liquid. 
After feeding, formicarius cleans itself elaborately. The 
vertex is rubbed by the prothoracic tarsi, usually both legs 
scraping together. The antennae are cleaned by pushing 
them between the slightly gaping mandibles from above. 
The antennae are then pulled back and forth, usually one 
at a time, in part by their own activity, but also by the 
fore-legs which push them upwards. After the antennae 
are cleaned they are withdrawn and the prothoracic tarsi 
and tibiae are thrust between the jaws, one leg at a time, 
and drawn back and forth rapidly. The front legs may 
also be rubbed together, after the manner of so many flies. 
The left elytron is scraped by the left middle leg and the 
right elytron by the right middle leg. The dorsal surface 
and sides of the abdomen are scraped by the metathoracic 
legs. Finally the wings are unfolded and held so that they 
parallel the abdomen, and moved from time to time. When 
the wings are retracted again, this action is aided chiefly 
by the raised apex of the abdomen. 
Another characteristic myrmecocole is the small psela- 
phid, Batrisodes globosus. It lives all the year round with 
Formica ulkei as one of its most abundant guests. This 
beetle, however, is reported with many kinds of ants. 
Blatchley (1910) records the species “in the large cone- 
shaped nests of ants/’ which may refer either to ulkei or 
exsectoides. Schwarz (1889-1890) reported this pselaphid 
from nests of Camponotus pennsylvanicus , Lasius ameri- 
canus , and Cremastog aster lineolata; Wickham (1898-1900) 
found it with Camponotus herculeanus , Lasius americanus, 
and Lasius aphidicola. Park (1982b) observed it with 
Lasius americanus, and I can now add the following hosts : 6 
6 I am indebted to Dr. Thomas Park and Dr. M. R. Smith for de- 
termination of these host ants. 
