FIELD BOOK OF INSECTS. 



niger is an ant which attends to the Corn-root Aphis, 

 Aphis maidi-radicis. During the winter this ant stores 

 the small black eggs of the aphis in its nests, moving them 

 from place to place as the weather changes. The eggs 

 start to hatch in early spring and the ants uncover the 

 roots of smart weed and of other plants in order to pasture 

 their cows. When, however, corn is planted, they transfer 

 the aphid stock to the corn roots, including such winged 

 aphids as may have developed and strayed from the fold. 

 A female aphis does not lay many eggs as compared 

 with insects in general, but development is so rapid (ten 

 days is not unusual, the eggs frequently hatching before 

 they are laid so that birth is given to living young) and 

 there are so many generations a season that the end result 

 would be extermination of all life by the destruction of 

 vegetation if it were not for counteracting agencies. Some 

 aphids are protected by ants, some by waxy secretions, 

 some by foldings and galls produced in leaves and other 

 parts of plants by their presence, but all are injured by 

 damp weather, by fungi and by insect enemies. Among 

 the latter might be mentioned Coccinelidae, Syrphidae, and 

 Chrysopidse, which, together with less important enemies, 

 devour them from the outside. But we should not over- 

 look the Chalcididae, which feed internally. Look at the 

 aphid colonies on a rose bush and you are almost certain to 

 see the dried shells of individuals which have been para- 

 sitized by these, our friends, a small hole in each showing 

 where the Hymenopteron had emerged. 



ALEYRODID.E 



This is the White-fly family. Aleyrodes vaporarium 

 (Plate XXIV) is the species most often found on house- 

 plants. The adults of both sexes have four wings and 

 seem to be covered with flour ; their wing expanse is usually 

 less than an eighth of an inch. The young somewhat 

 resemble scale-insects. As seen through a lens, they are 

 rather pretty, usually shiny black with white, wax-like 

 rods and tufts. Each egg is mounted on a small, curved 

 stem. Probably the majority of the American species are 

 still undescribed; they rarely appeal to amateurs and, for 

 the most part, they are of little economic importance. 



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