Common name: Aphids
Synonym: Blackflies, Greenbugs, Greenflies, Plant lice
Important aphid species
Black bean aphid (Aphis fabae
Corn leaf aphid (Rhopalosiphum maidis
Cotton aphid (Aphis gossypii
Cowpea aphid (A. craccivora
Greenbug (Schizaphis graminum
Groundnut aphid (Aphis craccivora
Soybean aphid (A. glycines
Cabbage aphid (Brevicoryne brassicae
Aphids are pests of vegetables, legumes, plantation crops, shrubs, flowers, fruit trees, and ornamental plants.
The mouths of the aphids are like tiny straws. The aphids, both the nymphs
and the adults, pierce the plant tissues to feed on plant sap. The leaf becomes severely distorted when the saliva of aphids are injected into it. The heavily infested leaves can turn yellow and will eventually wilt because of excessive sap removal. Aphids feeding on flower buds and fruits cause malformed flowers and fruits.
Aphids produce large amounts of a sugary liquid waste called honeydew
. A fungus, called sooty mold
, grows on honeydew deposits that accumulate on leaves and branches, turning leaves and branches black. The appearance of a sooty mold on plants is an indication of an aphid infestation.
In cotton, heavy infestation causes crinkling and cupping of leaves, defoliation, square and boll shedding, staining of the lints, and stunted growth.
In beans, the growing points are withered, brown, or dead. The leaves are crinkled and mottled. They become sticky because of black sooty mold growing on them. The plants are stunted and deformed.
In crucifers, the infested seedlings are distorted and stunted. Their continued feeding on mature plants causes wilting, yellowing and a general
stunting of the plants.
In corn, the leaves will wilt, curl, and have yellow patches. The tassels and silks are covered with honeydew. Damage, during the late-whorl and pollination stages, causes shortening of the inter-nodes, shriveled and shrunken ears, and empty cobs.
Eggs are very tiny, shiny-black, and are found in the crevices
of bud, stems, and barks of the plant.
Nymphs look like the young adults, they mature within 7-10 days, and are then ready to reproduce.
Adults are small, 3-4 mm long, soft-bodied insects with two projections on the rear end and two long antennae. Their body color varies from yellow, green, brown, to purple.
Females can give birth to live nymphs as well as can lay eggs. However, the primary means of reproduction for most aphid species is asexual
, with eggs hatching inside their bodies, and then giving birth to living young. Winged adults, black in color, are produced only when it is necessary for the colony to migrate, or there is either overcrowding in colonies, or unfavorable climatic conditions.