METHODS OF REPRESSION. 95 



destroyed by exposing the colonies with a shovel and scalding them 

 with hot water or spraying them with kerosene. At the senior 

 author's suggestion a number of small boxes filled with hay and trash 

 were placed at various points in the orchard. Wlien the water was 

 admitted it was found that the colonies moved into these boxes in 

 preference to going up the trees. They could thus be destroyed with 

 one flooding instead of two, as formerly. 



It may be remarked in passing that the ditches, when pains have 

 been taken to prevent the ants crossing them, have effectively limited 

 the spread of the ants tlu'ough the groves. This fact amply substan- 

 tiates our observations, mentioned on pages 19-20, to the effect that 

 colonies are never established by individual queens returning from a 

 marriage flight. Were colonies established in this manner, the areas 

 of infestation would not be sharply defined, nor would ditches retard 

 the dispersion of the ants from heavily infested centers. 



EXPERIMENTS WITH WINTER TRAP BOXES. 



The success which had followed experiments at Baton Rouge in 

 getting the ant colonies to concentrate during the winter in boxes 

 of decaying vegetable matter induced us to try the same plan in 

 an infested orange grove. Accordingly in November, 1910, a large 

 number of boxes, each 2 by 2 by 3 feet, of rough lumber, were made 

 and distributed tluroughout the infested block. Each was filled, 

 during the latter part of October, with a mixture of cotton seed and 

 dead grass. The top of each box was left exposed to the weather, 

 so that rain would enter to moisten the contents and start decay. 

 An examination of the boxes on November 16 showed that many 

 colonies liad entered them, but that many still remained in the 

 ground. To afford the ants less natural protection the orchard was 

 cultivated to remove the standing grass and weeds. In January, 

 1911, the authors again visited this orchard and found all boxes 

 filled almost to overflowing with enormous ant colonies. Each box 

 contained workers by the hundreds of thousands and queens by the 

 hundreds. A close examination in various parts of the orchard 

 showed, however, that not all colonies had entered the boxes. Some 

 few colonies had remained in their underground nests, particularly 

 where grass or weeds had been overlooked in the November cultiva- 

 tion and where, therefore, these colonies were afforded more protec- 

 tion than in the plowed portions. Wliether the already crowded 

 condition of the boxes had prevented other colonies from entering 

 them we could not determine. 



Experiments were now undertaken in destruction of the colonies 

 in the boxes. Metal covers had already been constructed for con- 

 fining gases in the trap boxes. (See PL XII.) Experiments were 



