Key Points:

  • Soybean aphids are small insects that use piercing-sucking mouthparts to remove plant sap.
  • Infested fields should be scouted frequently.
  • Foliar insecticides can be used to manage soybean aphids when populations surpass economic thresholds.

Pest Facts and Impact on Crop

  • Latin name is Aphis glycines Matsumura.
  • Origin in Asia.
  • First detected in U.S. near Lake Michigan in 2000.
  • Major outbreaks in 2001, 2003, and 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).

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 aphid distribution and area of increased probability of economic infestation.

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

soybean aphids 

Aphid-infested soybean leaves 

Pest Symptoms/Injury ID

  • Shortened plant height.
  • Curled leaves, often yellow on outside (similar to potassium deficiency).
  • Excessive honeydew on leaves, which promotes sooty mold.
  • Presence of ants, which also feed on the honeydew.

Natural Enemies

  1. Asian lady beetle – adult or larvae.
  2. Chrysopa/Lacewing – adult or larvae.
  3. Syrphid fly – larvae.
  4. Predatory bugs – Minute pirate bug, Big-eyed bug, Damsel bug, etc.
  5. Bio-control agent: Parasitic wasp – Binodoxys communis.
  6. Various fungal diseases

leaves blackened due to sooty mould 

asian lady beetle - adult or larvae 


Syrphid fly – larvae 

Predatory bugs – Minute pirate bug, Big-eyed bug, Damsel bug, etc. 

Bio-control agent: Parasitic wasp – Binodoxys communis. 

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 three stages:
    • Egg (fall and winter only)
    • Nymph (resemble small adults)
    • Adult (may or may not have wings)

soybean aphid adults on plant stem 

soybean aphid adults 

various soybean aphids and nymphs 

various soybean aphids and nymphs 

Various soybean aphids and nymphs

Management Practices

  • 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 two days)
  • Allow lady beetles, insidious flower bugs, and other beneficial insects to suppress populations
  • 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 non sprayed comparison of soybean aphids

  • Plant resistance
    • Natural antibiosis – Monitor varieties with least antibiosis first
    • Natural antixenosis

Life Cycle of the Soybean Aphid