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Aphids

Quick facts 

Aphids are one of the most common insects found on trees and shrubs, vegetables, annuals and perennials in home gardens. There are over 300 species of aphids in Minnesota.

  • In most cases they cause little or no damage to the health of trees and plants.
  • Signs of aphid feeding are: twisted and curled leaves, yellowed foliage, stunted or dead shoots, poor plant growth, and weak plants/trees.
  • In most cases natural enemies, like lady beetles and parasitic wasps keep aphid populations in control.
  • Treating aphids for the health of plants is usually unnecessary.
  • Aphids can be easily controlled with pesticides, but pesticides should be used only as a last option.

How to identify aphids

One small and one larger green, pear-shaped aphid on a green leaf
Aphid nymphs look similar to the adults

Aphids are small, 2-4 mm (1/16 – 1/8 inch) long, pear-shaped, soft-bodied insects. They can range in color from green, black, red, yellow, brown, or gray.

  • Fully mature aphids can be wingless or can have wings.

  • Adult aphids look like young aphids (nymphs) but are larger.

  • Winged adults are similar in color, but slightly darker because of their wings.

Brown aphid with blackish tailpipes at the end of the abdomen
All aphids have tailpipes

The best way to identify aphids is to check for the presence of two tail pipes (cornicles) found at the end of their abdomen.

  • All types of aphids have cornicles, but they might look a little different, based on the species.

  • Green peach aphids have long cornicles whereas cabbage aphids have short cornicles.

Aphids shed their exoskeletons (cast skins), as they grow. These white cast skins can be found on leaves or stuck in honeydew secretions of the aphid.

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Aphid damage

  • Aphid damage is generally minimal, especially when the plants are healthy and mature.
  • Aphids gather where they can feed on new succulent growth:
    • unopened flower buds
    • the underside of young leaves
    • developing stems, twigs, bark and roots.
  • Signs of aphid feeding: 
    • twisted and curled leaves
    • yellowed foliage
    • stunted or dead shoots
    • poor plant growth
    • weak plants and trees.
  • Wooly aphids leave accumulations of wax and shed skins on leaves, twigs and bark.
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How to protect your garden from aphids

Check your plants for aphids throughout the growing season. Make sure to check both leaves and stems for aphids.

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Common aphids in Minnesota

Pictures and descriptions of common aphids found in Minnesota are given below.

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More about aphids

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Jeffrey Hahn, Extension entomologist and Suzanne Wold-Burkness, College of Food, Agricultural and Natural Resource Sciences

Reviewed in 2018

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