Soybean Aphid


Pest Symptoms / Injury ID

Aphid-infested soybean leaves
Soybean aphid-infested soybean leaves.
  • Shortened plant height
  • Curled leaves, often yellow on outside (similar to potassium deficiency)
  • Excessive honeydew on leaves, which promotes sooty mold growth
  • Presence of ants, which also feed on the honeydew
Soybean field infested with soybean aphid

Plants infested by soybean aphid are shorter.

Facts and Impact on Crop

Pest Facts and Impact on Crop

  • Latin name is Aphis glycines Matsumura
  • Importance
    • Origin in Asia
    • First detected in U.S. near Lake Michigan in 2000
    • Major outbreaks in 2001, 2003, 2005
    • Untreated economic infestations frequently reduce yields by more than 10 bu/acre
  • Development
    • Overwinter on buckthorn, move to soybeans in July and back to buckthorn in the fall
    • Host plants include a wide range of legumes (soybean, alfalfa, clovers)

close-up of soybean aphid
U.S. map of soybean aphid distribution

Soybean aphid distribution and area of increased probability of economic infestation.

Causes of Yield Reduction
  • Removal of moisture, nutrients needed for grain production
  • Honeydew on leaves where sooty mold grows, which reduces photosynthesis
  • Transmission of viruses

Soybean leaves blackened due to sooty mold

Soybean leaves blackened due to sooty mold.

Natural Enemies

  • Asian lady beetle - adult or larvae
  • Chrysopa/Lacewing - adult or larvae
  • Syrphid fly - larvae
  • Predatory bugs - Minute pirate bug, Big-eyed bug, Damsel bug, etc.
  • Biocontrol agent = Parasitic wasp - Binodoxys communis
  • Various fungal diseases


Natural enemies of soybean aphids

Pest ID

  • Soybean aphids are small
    • Less than 1 mm in length
    • Oval or pear-shaped
  • Color is typically light green
  • Adults may or may not have wings
    • Winged adults have black head/thorax
  • Cornicles are distinguishing characteristic
    • Black "tail pipes" projecting from the rear of the abdomen
  • Aphids develop by gradual metamorphosis in 3 stages:
    • Egg (fall and winter only)
    • Nymph (resemble small adults)
    • Adult (may or may not have wings)
Soybean aphid nymphs and adults

Soybean aphid nymphs and adults

Life Cycle

Life cycle of the soybean aphid


Management Practices for Soybean Aphids

  • Population factors
    • Consider using seed treated with a nicotinoid insecticide to delay soybean aphid population establishment, especially in late plantings
    • Temperatures in the low to mid 70s promote longevity and reproduction (doubling time is less than 2 days)
  • Scout fields in July
    • Use economic threshold of 250 aphids per plant to justify insecticides
  • Insecticide control
    • Spray fields before aphids reach 1,000 per plant and plant stage R5.5
sprayed and unsprayed field for soybean aphids
  • Plant resistance
    • Natural antibiosis - Monitor varieties with least antibiosis first
    • Natural antixenosis
    • Future Pioneer® brand varieties with array of Rag genes may reduce need to spray