HOMOPTERA 419 



The appie-bud aphis, Rhopalosiphum prunifdlicB. — This is the 

 species that most commonly infests the opening apple-buds, often 

 nearly covering them. It also infests pear, pltim, quince, and many 

 other plants. It is a migrating species ; various species of grain serve 

 as its secondary host. 



C. ROOT-FEEDING APHIDIN^ 



The corn-root aphis, Anuraphis maidi-radlcis . — This is a serious 

 pest of com throughout the principal corn-growing States, sometimes 

 totally ruining fields of com. Broom-corn and sorghum are the only 

 other cultivated crops injured by it ; but it infests many species of weeds 

 that grow in corn-fields. Our knowledge of this species is largely the 

 result of investigations of Professor S. A. Forbes, who has published 

 several detailed accounts of it in his reports as State Entomologist 

 of Illinois. This author found that this aphid is largely dependent 

 on a small brown ant, the corn-field ant {Ldsius americanus) , the 

 nests of which are common in corn-fields. The ants store the winter 

 eggs of the aphids in their nests and care for them throughout the 

 winter. In the spring, when the stem-mothers hatch, they are trans- 

 ferred by the ants to the roots of the weeds upon which they feed. 

 As soon as corn-plants are available, the ants transfer the aphids to 

 the roots of the com, the ants digging burrows along the roots of the 

 com for this purpose. The ants in return for their labors derive 

 honey-dew from the aphids. 



One can understand how these ants that attend aphids that are 

 excreting honey-dew should learn to drive away the enemies of the 

 aphids, as is often done ; but is it not wonderful that Lasius americanus 

 should recognize the importance of preserving the eggs from which 

 their herds are to develop ! 



The strawberry -root aphid, Aphis forbesi. — The winter eggs of this 

 species are found upon the stems and along the midribs of the green 

 leaves of strawberry plants. The stem-mothers and one or more 

 generations of the offspring feed upon the leaves in the early spring. 

 But a little later in the season the corn-field ant appears and transfers 

 the aphids to the roots of the strawberry, where it cares for them in 

 the same way that in corn-fields it cares for the corn-root aphis. 

 This ant is entirely responsible for the infesting of the roots by the 

 aphids; and it is here that the greatest injury to the plants is done. 



Subfamily MINDARIN^E 



This subfamily was established by Baker ('20) for the reception 

 of the genus Mindarus, which can be distinguished from all other 

 living aphids by the venation of the wings. In this genus the radial 

 sector of the fore wings separates from vein Ri at the base of the 



