366 THE CANADIAN ENTOMOLOGIST 



means of a small pufifer or dust gun. The powder was dusted 

 into the openings between the beam and the roof, as also into 

 other cracks or openings nearby. The following morning the 

 ants were not nearly so noticeable, so I went over the ground 

 again on the evening of May 25. Since this last date, practically 

 no ants were s^en in our cottage in the places where previous to 

 the use of the sodium fluoride they were very abundant. The 

 result of our first test of the use of this chemical as a remedy for 

 ants in dwellings was so satisfactory that every opportunit\- of 

 further experimenting with it was taken ad\antage of. 



On May 27. I \ isited another summer cottage in the outside 

 kitchen of which the common shed-builder ant, Cremastogaster 

 lineolala, was present in countless numbers, causing much anxiety 

 from its hal)it of crawling over tables, shelves, etc. In this dwelling 

 the ants also frequented the beams supporting the roof. The 

 sodium fluoride was dusted into the cracks between the beams 

 and the roof and also on to shelves, etc., where the ants were present 

 in numbers. An examination was made of this kitchen during the 

 following evening and practically all the ants had disappeared, 

 only a few here and there being observed. Only one application 

 was made. The owner of this dwelling recently informed me that 

 no further annoyance was caused by the ants during the remainder 

 of the season. 



In other nearby cottages, too, the same results were obtained, 

 and from owners of summer dwellings on the Rideau Lakes and other 

 places in the vicinity of Ottawa, to whom recommendations were 

 made to use the sodium fluoride, the reports received have been 

 similar and in all cases satisfactory. In one instance in the city 

 of Ottawa the carpenter ant, Camponotus pennsylvanicus, was 

 present in annoying numbers in the kitchen of an apartment 

 house. The insects entered through a door which opened on to a 

 balcony. In this instance the sodium fluoride was simply dusted 

 on the floor near the door. After its use on tw^o occasions only 

 no further ants entered the apartment. In this latter instance 

 the powder was simply placed in a shell vial and dusted on to the 

 floor through a cheese-cloth covering which had been tied o\er 

 the opening. 



