nificant, but a few kinds of ants are capable of an indirect injury to corn 

 wliicli often becomes extremely serious. By the care and assistance given 

 to plant-lice, or aphides, which infest the roots and leaves of corn, they 

 greatly extend and increase the injury done by these insects which they 

 have in charge. This injury is mainly due to ants which live in corn 

 fields throughout the year, reinforced, as they are, by newcomers from 

 adjacent grass-lands in early spring. In their underground nests in the 

 field they collect in fall the eggs of the corn root-aphis, and in spring 

 they ])lace the young hat(!hing from these eggs on the roots of suitable 

 food-plants. As these grow and multiply, the ants transfer them from 

 one plant to another as necessity may arise, devoting themselves to their 

 welfare with a constancy and patience, due not to charity, as it might 

 seem, but to an enlightened regard for their own best interests. Through- 

 out nearly the whole season, indeed, these ants are dependent on their 

 helpless charges for food, which they find in the abundant fluids given off 

 by the plant-lice as these suck the sap from the growing plant. 



To the ant the plant-lice are living automatic pumps, constantly 

 drawing from the tissues of the plant excessive quantities of sap, abstract- 

 ing from this only a part of its food material as it passes through their 

 bodies, and giving it forth again in condition to serve a second time for 

 the support of insect life. A similar benefit is derived by other species 

 of ants from the corn leaf-aphis, but this insect is only slightly injurious 

 to corn, and the ants are less essential to it. Nothing is known, for 

 example, to indicate that the eggs of the leaf-aphis are cared for by ants, 

 and, indeed, no eggs of this species have ever been found. 



With the exception, therefore, of the various species of ants which 

 attend the corn root-louse in the earth, injin-ies to corn by these insects 

 may be practically ignored as insignificant, and at worst as not serious 

 enough to require or warrant attempts at measures of prevention. 



Diptera: Flies and Gnats. — Among the nmltitudes of two-winged 

 flies, or Diptera, only a few are found frecpiently on or about the corn 

 plant, and scarcely one of these is likely to do it any serious injury. 

 The winged insects themselves are never injurious to corn, all the harm 

 done by these insects to this plant being through their larva or maggots 

 only. When corn has followed upon clover, the roots of the young plant 

 have rarely been injured by the large, dirty-looking, grub-like larvaj of 

 one or two of the crane-flies (Tipulidcc) ; the planted seed is sometimes 

 eaten to some extent by the small seed-corn maggot (Pegomyia fusciceps) ; 

 the leaves are occasionally mined in a very small way by two or three 

 mining maggots (Diastata and Ceraiomyza dorsalis); and the larva of a 

 Syrphus fly, which commonly feeds on the fallen pollen' lodged in the 

 tassel or at the tip of the ear or at the base of the leaf, is reported some- 

 times to piuicture the leaf for the sake of the sap. Other Syrphus larvae 



