92 



FARM FRIENDS AND FARM FOES 



easy for the migrating females to find suitable food, and it 

 also renders the pest very difificult to fight successfully. 



Ants and Aphides 



One of the most interesting things about the aphides is 

 their relation to various kinds of ants. If you look at a 

 colony of plant lice upon almost any tree or shrub, you will 

 probably find at least one kind of ant wandering around 

 among the aphides, and very likely you will find a regular 



procession of ants go- 

 ing up and down the 

 trunk -of the tree or 

 shrub. If you watch 

 one of these ants care- 

 fully, you will probably 

 see it find a plant louse, 

 touch it with the feelers 

 or antennae and very 

 likely lap up a drop of 

 liquid exuded by the 

 aphis, for these ants 

 visit the plant lice to obtain the liquids that pass through 

 their bodies. In consequence, the plant lice are sometimes 

 referred to as the milch cows of the ants. 



There are many strange and interesting things to be found 

 out concerning the relations of the ants and the aphides. 

 To a very large extent, many species of aphides find friendly 

 helpers in the ants. One of the most interesting examples 

 of this is the case of the Corn-root Aphis, an insect often 

 very destructive to corn crops in the Mississippi Valley. 



This Corn-root Aphis is constantly attended by a small 

 brown ant that burrows out tunnels along the corn roots in 

 order that the plant lice may have a place to live. As the 



Ant attending Aphides upon a Wii-low 

 Twig 



