aphid(redirected from plant louse)
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aphidany member of the family Aphididae, order Hemiptera, commonly called green fly. Aphids feed on plant juices by using piercing and sucking mouthparts and are of considerable economic importance because they can act as vectors of plant viruses. See Fig. 41 .
an insect of the order Hemiptera. They parasitize many plants during the warm seasons. Of interest in animal health are the black aphids, Aphis craccivora, which can exist in very large numbers on burr trefoil, Medicago polymorpha, and may stimulate the production of phytoallexins in the plant which then photosensitize animals grazing the infested pasture.