August, '111 NICKELS: ARGENTINE ANT 355 



the summer cracks offer a multitude of excellent nesting places, many" 

 stone sidewalks make disturbance of the colonies underneath impos- 

 sible, so that on the whole the block is very favorable for the success 

 of ants, and being successful proved amply that the average battle 

 against the ant is fought upon the wrong end of the invasion. 



For those who are not famiUar with the control meiasures suggested in 

 Bulletin 207, I will outline them briefly. A sponge moistened with 

 sugar syrup containing 1-4 to 1-8 per cent sodium arsenite (Na As O2) 

 is placed in a suitable container with a perforated cover. The ants 

 visit this receptacle and carry the syrup to the nest where it is fed to 

 the brood and to the queen, slowly poisoning them, shutting off the 

 increase of the colony which ultimately means utter extinction. 



The next step after examining the territory was to prepare the poison. 

 Pint screw-top jars have been found the best, easiest to handle and 

 least liable to injury by exposure, of the more easily obtainable recep- 

 tacles. The tops are prepared by breaking out the porcelain cap and 

 making four holes with any suitable implement. A twenty-penny 

 nail with its point filed flat and a round block made a very good punch- 

 ing outfit. One should expect to prepare about 100 jars an hour by 

 this method. In all we are using about 350 jars, 300 furnished by the 

 city and the remainder from the University stock (about 150 are 

 being used in the block under discussion). 



During this operation the first lot of poisoned syrup was prepared, 

 using 20 pounds of sugar, — 6 to 7 pounds of water and a fraction over 

 an ounce of the arsenic, this being 1-4 per cent of the total weight. 

 Sodium arsenite contains about 57 3^^ per cent of arsenic so that the 

 above quantity falls within the established limit. It was found 

 necessary to heat the syrup mixture for about three hours in a water 

 bath. The arsenite should first be dissolved in hot water before it 

 is added to the sugar solution. In places where cheap molasses can 

 be obtained, this could doubtless be used. On the Pacific Coast 

 granulated sugar will give the cheapest syrup. About ten pounds of 

 the liquid syrup to every one hundred jars is necessary for the first 

 charging. 



Ten pounds of sponges cut to about one half the size of the interior 

 of the jar will give a sufficient number for 300. In manipulating the 

 sponges it is best to sharpen the cutting knife after every slice and 

 have them moist. This aids cutting and in the absorption of the sugar 

 solution. The jars can be most quickly charged by first inserting the 

 sponge and then pouring on about one half a gill of the liquid. 



In beginning the actual poison work it was thought best to start 

 on the most difficult situations. In the light of this the hotel was 

 chosen as the starting point, 50 jars were distributed, mainly about 



