Aphids - Vegetables

 aphids

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Appearance Adults: Small, soft-bodied, tear-drop shaped, ranging in color from green to blue-green, yellow, orange, red, black and grayish white. Some are covered with fluffy white wax. Most have a pair of tubular cornicles near the tip of the abdomen (looks like a “dual-exhaust” system). Dispersing adults have wings.
Immatures: Resemble adults.
Life Cycle/Habits

Eggs laid in fall overwinter and hatch in spring.  Many more generations are produced during the growing season.  Aphids move slowly, congregating on new succulent growing tips and leaf undersides. Winged dispersing adults may fly to other plants. Aphids have long slender mouthparts to suck plant sap, and excrete sticky honeydew.  Aphids feed on plant leaves, stems or roots, depending on the species, and can transmit plant diseases.

 
Video contributed by Mike Raupp

Host Plants A wide range including: beans, beets, broccoli, Brussels sprouts, cabbage, cantaloupes, cauliflower, collards, cucumbers, eggplant, kale, peppers, potatoes, pumpkins, radishes, spinach, squash, tomatoes, turnips, watermelons.
Signs/Symptoms Sucking of sap stunts plants. Leaves curl and/or discolor with white or yellow stippling. Sooty mold may grow on honeydew, blackening leaves. Aphids congregate on new growing tips, but are also attracted to lush, overly fertilized growth or stressed plants.
Monitoring Examine transplants to intercept infested plants. Check leaf tips and undersides and along stems for clusters. Inspect for sooty mold growing on honeydew. Note any curling, stunting, or stippling. Ants frequently harvest honeydew from aphids, so the presence of ants may be a sign of aphid infestation.
Prevention/Control
  1. Do not plant infested transplants.
  2. Aphids are mainly a problem May through June, but have many natural enemies (e.g. lady bird beetles, lacewings, syrphid fly, parasitic wasps) that keep numbers controlled. Look for brown, swollen parasitized bodies.
  3. Encourage predators with attractant plants and avoid toxic pesticides.
  4. Control low aphid infestations with a robust spray of water.
  5. If damage is obvious and predators and parasitoids few, use insecticidal soap. Check product label for directions before spraying. 

Aphids photo gallery - click an image to enlarge

aphid adults and cast skins

Aphid adults and cast skins.

close up of aphids, J. A. Davidson, U of MD
Close up of aphids.
Photo: J. Davidson, UME
Lady bird beetles eating aphids on tomato
Lady bird beetles eating aphids on tomato.
close up of aphids and honeydew
Close up of aphids and honeydew.
corn aphids. C. McClurg, UME
Aphids on corn.
Photo: C. McClurg, UME
cabbage aphids
Aphids on cabbage.
potato aphids. Galen Dively, UME
Aphids on potato.
Photo: G. Dively, UME

Related publication: HG 83, Aphids on Ornamental Plants

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