' THE ARGENTINE ANT. 19 



MEANS OF DISPERSION. 

 NATURAL SPREAD. 



Under strictly natural conditions, the rate of dispersion of Argen- 

 tine ants is very slow. Owing to their intensely social habits they 

 spread but slowly from a locality until the number present becomes 

 excessive for the food supply or unless adverse conditions, such as 

 flooding, occur which compel them to seek fresh locations. They 

 will then spread in all dhections, but will go little farther than is 

 necessary to give them sufficient foraging area to insure the food 

 required. However, if a large food supply is discovered at a con- 

 siderable distance from the colony, a heavy trail of workers will 

 soon be formed between the food and the nest, composed of many 

 thousands of tiny insects, each busy carrying a load of the coveted 

 material back to the nest or going out for another load. Sometimes 

 they will construct a new nest in the neighborhood of the food sup- 

 ply, and to this they will transport a number of pupae, larvae, and 

 eggs from the parent nest. In the course of a day or so this new 

 colony Avill be thoroughly established, with a full supply of queens, 

 workers, and immature stages, and will then be capable of supporting 

 itself and increasing in numbers without assistance from the parent 

 nest. 



Under normal conditions it is likely that the rate of spread does 

 not amount to more than a few hundred yards each year. When 

 food is plentiful, a well-traveled road or a paved street may restrict 

 the spread for a considerable period, but when any much-desired 

 food supply, such as the excretions of aphides or scale insects, is to be 

 reached, nothing short of running water proves an effective barrier. 



It is possible, but scarcely probable, that the queens may aid the 

 natural dispersion by means of flight, but there are several reasons 

 why this is doubtful. One of them is that the flight itself is a very 

 uncertain event, as during the five years that these ants have been 

 studied in Louisiana only one general fiight has been observed. It 

 has been established that the young queens can mate in the nest 

 without taking a marriage flight at all, and apparently this is what 

 usually takes place. Even should a fertilized winged queen fly or 

 be transported by the wind to any considerable distance from the 

 ant-infested territory, it is very doubtful whether any eggs she might 

 lay would ever hatch. The queen has never been observed assisting 

 in the slightest degree wath the rearing of the young in the nest, nor 

 have we succeeded in getting eggs to hatch when they were not 

 cared for by the workers. As the workers are never wanged, the 

 queen would necessarily be alone, and it would be very unlikely 



