1929] 
Myrmecocoles of Formica ulkei 
201 
Conversely, when a Leptinus came into contact with an 
ulkei worker it usually crouched to the substratum, remain- 
ing motionless, and seldom ran away. 
Similarly, the leptinids were apparently not molested by 
the pselaphids (Batrisodes globosus and B. denticollis) , and 
vice versa, nor were the pselaphids attacked by the ants. 
In another series of observations, leptinids were isolated 
with the carabid, Tachyura incurva. In one petri dish, out 
of three used, the leptinids were unmolested. In the other 
two nests, each having one Leptinus and three Tachyura, 
the Leptinus were completely devoured within twenty-four 
hours save for the meso- and meta-sterna and the elytra. 
Further details on the carnivorous behavior of these cara- 
bids will be given later, however it is interesting to note 
that when a leptinid was met by Tachyura in the laboratory 
nests it frequently darted out of the latter’s path. 
Food 
Just what the food of testaceus consists of has been gen- 
erally guessed at and in view of the controversial nature of 
its status with its many hosts, some knowledge of its feed- 
ing habits should be of interest. 
A simple leptinid was placed in each of six petri dish 
nests and given no food by the experimenter for two days. 
Obviously, during this time it may very well have caught 
and devoured small organisms in the soil taken from the 
ulkei nests placed in the dishes, which could not be readily 
removed, e.g., small acarinids (Gamasoidea?) . 
At the end of two days, viz., the second night, a de- 
pressed slide full of sugar syrup was placed in each dish. 
Two of the leptinids were observed to halt at the slide. 
These two lowered the head and prothorax and after tap- 
ping about with their antennae, moistened their palpae and 
mandibles in the solution. The other two either went 
around the syrup, or turned back on their path. It is pos- 
sible then, that testaceus will feed on occasion on sugar 
syrup. Mere moisture was certainly not at a premium in 
the petri nests as one section of the soil was kept saturated 
with water. 
