THE ARGENTINE ANT: DISTRIBUTION AND CONTROL. 15 



greatly modified sirup. In all the experiments the sirup proved very 

 attractive and palatable to the ants at first, but their visits gradually 

 decreased until the sirup was avoided, although in some instances the 

 trails continued to pass by the poison jars. The period of attendance 

 at the sirup varied somewhat with the seasons, being longer in winter. 

 Even in the winter, however, a repellent action was apparent. In 

 preparing the solution it had been noticed that the sirup turned 

 brown, becoming darker the longer it was boiled, although it was 

 made in a pail which in turn was placed in a bath to prevent burning. 



Another objection was the crystallization of the sirup to a greater 

 or less extent upon cooling. On the advice of a sugar chemist the 

 proportion of water was increased to make a saturated sugar solu- 

 tion ; 10 pounds of water to 20 pounds of sugar and 1 ounce of sodium 

 arsenite were used. The Nickels sirup, contained one-fourth per cent 

 arsenic, while this more dilute sirup contained one-fifth per cent, 

 but the dilute sirup was quite effective. With the exception of the 

 first application, the dilute sirup was used throughout the length 

 of the Hattiesburg experiment. Crystallization of from 5 to 15 

 per cent of the weight of sirup still occurred in short periods, but 

 as high as 50 per cent when the sirup had been in the jars for several 

 months. This of course had the effect of proportionally increasing 

 the percentage of poison in the liquid and consequently its repellent 

 power. Newly made sirup appeared to be less repellent than that 

 which had stood for several weeks. 



The repellent action of the sirup is illustrated by an experiment 

 conducted in a private residence, which was badly overrun with ants. 

 The ants were abundant in the refrigerator, safe, and sink, and literally 

 covered the floors. Six fruit jars containing the Nickels sirup and 

 sponges were placed in different rooms in the house, and 6 paraffined 

 paper bags containing the same sirup and a sponge were placed 

 around the house outdoors on trees, fence, and back porch. The 

 sirup was about a month old. The experiment was begun at 1 p. m. 

 At 5 p. m. hardly an ant was to be seen in the house, although a few 

 Avere to be found at each jar and many were visiting the bags. Two 

 days later .not an ant could be found in the house and only three erf 

 the bags were attended by ants. As it seemed impossible that the 

 colonies could have been exterminated so quickly, the adjacent vacant 

 lot was inspected. This lot was overgrown with weeds, and in a 

 corner near the house there was a pile of old lumber. Ants were 

 found in abundance nesting in the lumber, and many were present 

 wherever they could find dry quarters in the lot. It was quite evident 

 that the ants had been repelled by the poison. 



A series of experiments to obtain definite data on the repellent 

 properties of the sirup were conducted in the Horticultural Hall, 



