354 ANTS. 



placing the recently hatched plant-lice on the stems and roots of the 

 plants, rorhes. \\Ved and Webster have shown that our common L. 

 (iincriciiints is thus instrumental in rearing and disseminating through- 

 out the h'elds a root aphid (.-I phis inaidiradicis ) which is very injurious 

 to Indian corn. Webster gives the following account of his extended 

 observations on the relations of these insects to each other: "Now, 

 taking up the life history of the root-aphis, we find eggs in the fall, it 

 is true, but only in the burrow of and attended by these ants. 1 f there 

 are eggs, egg-laying females, or males elsewhere they have yet to be 

 discovered. The ants care for these eggs throughout the winter, shift- 

 ing them about, according to Forbes, as they do their own young, to 

 accommodate them to changes of weather and moisture. In spring, 

 the young, as soon as they hatch from these eggs, are transferred by 

 the ants to the roots of young fox-tail grass, smart- weed, and even rag- 

 weed. The young are carried out to pasture, as it were, during fair 

 weather, but in bad weather, or on cold nights, they are taken back 

 to the burrows of the ants. The plants just mentioned are the ones 

 that push up early in spring in last year's corn lands, and especially in 

 fields that have been plowed and allowed to stand untouched for a 

 week or so. Usually the farmer plows his ground in spring and pays 

 little attention to this early growth of weeds and grass, as he can gen- 

 erally dispose of it as soon as he begins to cultivate the corn, although 

 this is not until the rows of young plants can be followed by the eye 

 across an ordinary field. As soon, however, as the corn plants begin 

 to show above ground the ants not only transfer the young root-aphids 

 from the burrows to the roots of corn, but they will also remove them 

 from the roots of grass and weeds and recolonize them on the roots 

 of young corn. Now these young aphids are all females and within 

 a few days they begin to give birth to young, also all females ; these, 

 too, are cared for by the ants, which place them on the freshest and 

 most tender rootlets. This procedure goes on about the roots of corn 

 throughout the spring and summer. Forbes has found that under the 

 most favorable artificial conditions there may be as many as sixteen 

 generations between April and October, ten of which may coexist 

 at the same time. It is hardly probable, however, that so many genera- 

 tions can exist under ordinary field conditions ; nevertheless, it may be 

 rightly inferred from this that the multiplication of the species is enor- 

 mous. These ants not only transfer the root-aphids from one root to 

 another of the same plant, but will carry them from one plant to another 

 a considerable distance away. In the spring of 1887 the writer placed 

 a number of flower pots containing young growing uninfested corn 

 plants between rows of infested hills of corn in the field. The corn 



