1937] 
Habits of Strumigenys 
101 
We now come to another postulate concerning the habits of 
Strumigenys which was advanced by the author in a paper 
published in 1980 (4) . This publication, primarily concerned 
with the genus Myrmoteras, carried introductory remarks 
on various genera possessing linear mandibles. The matter 
of retrosalience was necessarily discussed but I attempted 
to show that this phenomenon represented the fortuitous 
outcome of a type of mandibular organization which I styled 
“trap-jawed”. I pointed out that such mandibular apparatus 
would be a very decided advantage to sluggish ants enabling 
them to capture other insects more agile than themselves. 
It is gratifying to be able to state that this supposition has 
proven correct in the case of Strumigenys. Because much of 
what is to follow presupposes a knowledge of the structure 
of the mandibles of Strumigenys I have prefaced the account 
of their activities with the needful morphological description. 
Each mandible of S. louisianae subsp. laticephala (Fig. 1) 
is inserted close to the midline of the head and consists of a 
rather stout blade which is rounded on the outer face and 
flattened on the inner. This blade bears two prominent 
apical teeth and a third subapical tooth which is about half 
as long as the other two. All three teeth are sharp and 
slender and set at right angles to the long axis of the blade. 
As the tip of the blade is somewhat rounded at the rear of 
the two apical teeth the resulting structure is not unlike 
what would be produced if the tines of a fork were bent at 
right angles to the handle. There is, however, this differ- 
ence, the “fork” has only two tines and these are separated 
by the thickness of the blade of the mandible. There is thus 
a considerable space between the apical teeth, a fact which 
will be later shown to be of importance. When in repose the 
mandibles can be brought close together so that their inner 
faces are almost in contact. This appears to be the usual 
Vol. 47, No. 7, pp. 171-174, 1936.). Mr. Wesson showed that the normal 
food of this ant consists of various species of springtails. The 
Collembola are hunted down by the ants but not seized until they 
blunder into the open mandibles of their captors. Mr. Wesson con- 
siders that the presence of various species of Strumigenys in the nests 
of other ants constitutes what he calls a “loose form of symbiosis.” 
The Strumigenys benefit because of the abundant supply of springtails 
and are tolerated by the other ant which may benefit by the removal of 
the springtails. 
