. Circular. Insects. 3 are born alive, after the manner of mammals, and all are fertile females. It will therefore be very clear that with no knowledge of the males and with only this fragment of the life cycle of the females it is impossible to say whether the leaf-aphis is an above-ground form of the root-aphis or whether it is distinct from and wholly inde- pendent of that insect. FIELD EXPERIMENTS. In October, 1885, the writer transferred some volunteer plants of corn from the field of fall wheat, where they were growing, to some breeding cages. The plants were thickly populated with winge
. Circular. Insects. 3 are born alive, after the manner of mammals, and all are fertile females. It will therefore be very clear that with no knowledge of the males and with only this fragment of the life cycle of the females it is impossible to say whether the leaf-aphis is an above-ground form of the root-aphis or whether it is distinct from and wholly inde- pendent of that insect. FIELD EXPERIMENTS. In October, 1885, the writer transferred some volunteer plants of corn from the field of fall wheat, where they were growing, to some breeding cages. The plants were thickly populated with winged females of the leaf-aphis, and these were carefully secured with the plants, both being subjected to the same conditions which would have influenced them had they remained in the held, except that the ants in attendance were excluded. On May 8,1886, corn was planted in these cages and grew therein till after the 15th of June—when it was thrown out—without a single individual of either root or aerial form of the root-aphis being on or about the plants. Dr. S. A. Forbes, State entomologist of Illinois, under whose direction most of the investigations of these insects have been carried out, in summing up the results of a long series of carefully conducted experi- ments of his own, comments as follows: The foregoing data confirm our ignorance more than thev increase our knowledge, showing, as they , /.. , f ' , , Fig. 2.—The corn leaf-aphis (Aphis do, the failure of all attempts to find or produce a maidis): Wingless female. Much bisexual generation or an alternative food plant of enlarged (original). Aphis maid is, or to learn how and where it normally passes the winter. Its willingness to feed on wTinter wheat and ability to breed freely on that plant, its indisposition towrard grass or the foliage of the apple, and the natural frequency of successive generations, are the principal other facts evident from these Winged females of the root-aphis occur in sum
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