506 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



rice in Louisiana and Texas. The primary work was to investigate 

 the life history of this insect, concerning which very littJe is known. 

 At the same time plans were made for testing remedial measures. 

 Among the most promising of these are certain changes in manipula- 

 tion of the water used for irrigation. As the insect is of an aquatic 

 nature, it seems probable that deferred flooding of the field or the 

 withdrawal of water for a short time during the growing season 

 may result in considerable relief. Experiments with a number of 

 modifications of the system of managing water were instituted at 

 Crowley, in cooperation with the Louisiana Rice Experiment Sta- 

 tion, and also at Stuttgart, Ark., in cooperation with the Division of 

 Irrigation Investigations of the Office of Experiment Stations. 



AEGENTINE ANT INVESTIGATIONS. 



The work on the Argentine ant problem was continued. Life-his- 

 tory investigations were carried on, and experiments were made to 

 discover effective means of control. Several fresh centers of infesta- 

 tion were discovered, so that the area affected is much larger than 

 had been supposed. Remedial work was restricted largely to experi- 

 ments in orange orchards in Louisiana. Here the ant has threatened 

 to destroy a very profitable industry. It was found during the pre- 

 ceding year that large numbers of the ants could be attracted to 

 shelter provided in boxes placed at convenient points throughout the 

 groves. In many cases all of the ants in the field appeared to make 

 their way into these shelters, and the experimental work in the way 

 of destroying them in these shelters indicates that a very efficient 

 means of control has been discovered for this insect under orchard 

 conditions; but the method is not well adapted to city surroundings, 

 where the ants find winter quarters under houses almost as attractive 

 as the trap boxes. Hydrocyanic-acid gas was found not to have suffi- 

 cient penetrating power to work with the traps, but bisulphid of 

 carbon ultimately proved to be very effective and penetrated to the 

 most remote corners of the trap boxes. 



COTTON BED SPIDER INVESTIGATIONS. 



Prior to 1910 some observations on the cotton red spider had been 

 made by occasional trips of agents of the bureau to Batesburg, S. C, 

 and other points in that State. During 1910 an agent was detailed 

 for continuous work on this problem. He was stationed at Batesburg 

 early in the season, and remained there until September 1. His work 

 appears to have resulted in two important discoveries, both of 

 which, however, are subject to verification from further studies. 

 One of the discoveries is that the red spider does not pass the 

 winter in the cotton fields, but spreads into the fields from a small 

 number of wild or cultivated plants which remain green during the 

 winter and afford it an opportunity for early breeding in the spring. 

 The second discovery is that a modification of the well-known lime- 

 sulphur mixture, if applied with sufficient thoroughness, will destroy 

 the red spider in all stages. 



Experiments in cultural methods of controlling this pest were 

 conducted. Unfortunately, however, it appears doubtful at the pres- 

 ent time whether such methods will furnish means satisfactory to 

 the planters. 



