26 JOURNAL OF ECON'ONriC EN'TOMOLOGY . [Vol. 9 



they have also been found injuring seed corn. Within a day or two 

 after the seed is planted the ants attack it, hollowing out the kernel 

 and generally preventing germination (PI. 2, figs. 6 and 9). During 

 the past four years thousands of acres of sorghum crops have had to 

 be replanted from one to six times because of the ravages of this ant 

 and in a number of cases it has been impossible to obtain a stand. 

 With seed at $3.00 a bushel, as it was in 1914, this means a consider- 

 able money loss as well as time and labor spent in replanting. 



Methods of Study 



Considerable difficulty was encountered in finding a satisfactory 

 method of rearing this ant under artificial conditions that would 

 permit of daily examination. Because of the minute size of the work- 

 ers, such cages as the Lubbock, Janet, and Fielde proved unsatisfac- 

 tory. Finally, a modified type of the Janet cage was constructed, 

 which, although not entirely satisfactory, proved useful. This cage 

 (PI. 2, fig. 8) is made by moulding a block of plaster of Paris in an 

 ordinary dinner plate or saucer, having the upper surface level with the 

 top of the dish. On one side a small cavity is cut away for a water 

 chamber, which can vary in size according to the size of the cage. 

 Opposite this an oblong chamber about one-eighth inch deep, two to 

 three inches wide, and four to five inches long, is hollowed out and the 

 half of it farthest from the water reservoir is painted black and covered 

 over with a small square of glass. This gives a covered and an uncov- 

 ered chamber. The former is covered with a small square of black 

 cloth, making a very satisfactory dark chamber which can easily be 

 uncovered to permit examination. The uncovered area is used for a 

 food chamber, which readily permits of the removal of old or decayed 

 food. To prevent escape of the ants the food chamber is completely 

 surrounded by a barrier of vasehne, which must extend up and over 

 the adjacent edge of the glass covering the dark chamber. An extra 

 safeguard is had in placing a thin layer of vaseline around the dark 

 chamber before the glass top is put on. This not only fills up any 

 small crevices through which the ants could escape, but also prevents 

 the glass cover from slipping out of place. By making the dark room 

 near the edge of the dish, forms in the nest can easily be examined on 

 the stage of a binocular. 



This cage is not altogether satisfactory as the ants will sometimes 

 burrow through the plaster of Paris into the bottom of the dish. 

 Before ants become accustomed to the vasehne many are caught in 

 it, especially the winged forms, but after a time they learn to avoid it. 



