78 THE ARGENTINE ANT. 
self-evident, for the number of workers 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 various substances 
which had been used in successfully repelling other species of ants. 
Experience with artificial formicaries and with the hives 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, settling from the air, formed a very thin, 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 will 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 still. 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 will 
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 limited. 
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 which kept the ants within his 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; 
