78 THE ARGENTINE ANT. 



self-e^^(lent , for tlio number of Avorkcrs leaving a colony during any 

 given period is little if any greater than the number reaching maturity 

 within the colony during the same period. 



In spite of these facts repellents are very desirable and their use is, 

 under most conditions, absolutely imperative in the protection of 

 foodstuffs, such as sugars, candies, cakes, molasses, honey, vegetable 

 oils, fresh meats, etc. 



EXPERIMENTS WITH REPELLENTS. 



Our first experiments consisted in testing the A^arious substances 

 which had been used in successfully repeUing other species of ants. 



Experience \nth artificial formicaries and with the liives of honey 

 bees very quickly showed that water would deter the workers for only 

 a short time. In our first experiments with colonies kept under 

 observation the nests were placed on platforms supported above trays 

 of water. As soon as the water had stood for a few hours minute 

 dust particles, settl'mg from the air, formed a very tliin, almost imper- 

 ceptible scum on it, and this the workers traversed with ease. A 

 scum which, when viewed by reflected light, is barely perceptible to 

 the eye aatJI support the workers. When such standing water was 

 removed and fresh substituted for it the ants would plunge into it as 

 before, evidently expecting the scum to be there stiU. Instead of 

 drowning, as might be expected, the workers merely swam, or crawled 

 upon the bottom of the tray until they reached the edge or the wooden 

 support of the nest, when they proceeded to crawl out. Workers 

 thrown into water can readily crawl up one's finger or up a stick if it 

 is brought near them. The senior author has observed workers 

 which had accidentally fallen into a glass decanter three-fourths full 

 of water gain a foothold on the smooth glass sides and crawl out suc- 

 cessfully, feet up and body down, on the wet glass. The workers wiU 

 apparently not enter fresh water voluntarily, but evidence indicates 

 that they will sometimes do so in the attempt to reach their nests or 

 to reach some much-desired food supply. When running over a film 

 of oil or dust upon the water the feet and legs do not get wet, but 

 when the film breaks through, as sometimes happens, the worker 

 swims with her legs and a portion of the body submerged. Running 

 water, such as a stream in a ditch or trough, seems to be a successful 

 repellent, but the practical uses of such a stream are very hmited. 

 The use of running water as barriers to prevent the spread of infesta- 

 tion in orange groves is more fully described upon a subsequent page. 



Sir John Lubbock in his book, "Ants, Bees and Wasps," describes 

 bands of fur wliich kept the ants within liis artificial formicaries. 

 The kind of fur used by Sir John Lubbock is not specified, but the 

 finest we were able to secure was that from an ordinary "cottontail" 

 rabbit. With this the following experiment was made: 



