Population Studies of the Slave‐Making Ant Leptothorax Duloticus and Its Slave, Leptothorax Curvispinosus

In 1935 Laurence Wesson, working in Jackson County, Ohio, found a new slave-making ant which he named Leptothorax duloticus. These were enslaving ants of their own genus-L. curzYispinosus Mayr and L. longispinosus Roger. Wesson collected alive three of the four mixed colonies which he saw and was unusually successful in maintaining and observing them. In two papers (Wesson 1937, 1940) he described workers, males and females and recorded his observations of three raids made by colonies in the laboratory. No further accounts of finding L. duloticus have been published. (Creighton, in his 1950 revision of the ants of North America, lists its range as Ohio and Illinois, but he and others contacted were unable to trace any knowledge of the Illinois record.) In 1954 the writer found it in Livingston County, Michigan, at the Edwin S. George Reserve. Shortly after L. duloticus was discovered at the Reserve, Paul Kannowski informed me that he had taken it near Ann Arbor, Washtenaw County, Michigan. It may be that L. duloticus is a very rare and local ant, or it may be that it has been overlooked because it is so similar in structure and color to the yellow L. curvispinosus, which it usually enslaves. Under the microscope the stout, widespread spines, broad postpetiole and dusky tinge to the yellow color distinguish it readily, but these differences are difficult to observe in the field.