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Corn+Soybean Digest

Soybean Insects



  • SYMPTOMS: Plant sap is removed via sucking from the small, yellowish, glob-shaped aphid, causing leaves to wilt and curl. If numbers are high, leaves may become yellow and distorted; the plant may be stunted, covered in dark, sooty mold. From seedling to blooming, aphids will colonize tender leaves/branches, later moving down to colonize near the middle/lower underside of leaves and stem.
  • TIME OF ATTACK: V1-V2 on upper leaves, petioles, stem (scout twice/week); R1-R4: on undersides of mid-canopy leaves, stems.
  • CONDITIONS FAVORING: Northern states with cooler summer temps; fields with previous aphid populations; late plantings; crops stressed by hot, dry weather; high overwintering populations.
  • MANAGEMENT: Foliar-applied insecticide when populations reach 250/plant and continue to increase and 80% of field is infested; time treatment to maximize effectiveness. Beneficial lady beetles could help in control.


  • SYMPTOMS: Feeding is identified by small, round holes between veins. Entire pods may be clipped and the outside layer of pod tissue entirely consumed. Beetles feed on plants at all stages of development. Overwintering populations feed on cotyledons and leaves. The next generation feeds on leaves and the final generation feeds on leaves and pods.
  • TIME OF ATTACK: All season; first generation: late V, early R; second generation: pod-fill stage.
  • CONDITIONS FAVORING: Early planting and above-normal summer temperatures. Late-planted fields and below-normaltemps cancause better conditions for second-generation beetle pod feeding.
  • MANAGEMENT: Timely application of rescue treatment if sampling/defoliation threshold is reached.


  • SPECIES: Redbanded, Southern green, Brown, Green
  • SYMPTOMS: Flat pod syndrome and delayed maturity; brown and green species attack pods and seeds. Feeding punctures cause small brown/black spots. Young seeds can be deformed or undersized; older seeds become shriveled and discolored.
  • TIME OF ATTACK: R1-R7 reproductive stages.
  • CONDITIONS FAVORING: High populations of bugs and vulnerable growth stages; common along Louisiana and Texas Gulf coast.
  • MANAGEMENT: Cultivar selection and planting date. Rescue insecticide treatments when threshold reached while scouting. Populations also partially suppressed by predators and parasitic wasps.


  • SYMPTOMS: Leaves appear sandblasted. Heavily infested leaves turn red-brown and die. Webbing may be present on undersides of leaves. Heavy infestation causes leaves to wilt and die.
  • CONDITIONS FAVORING: Drought conditions
  • MANAGEMENT: Treatment by air or ground application if infested areas increase in size (no established threshold). Cool, wet weather conditions may reduce infestation.


  • SYMPTOMS: Feeding from inside-out on plant canopy. Defoliation leaving ragged appearance.
  • TIME OF ATTACK: Mid- to late season in the South.
  • CONDITIONS FAVORING: Use of pre-bloom insecticide that kills off natural enemies; late-planted, double-crop soybeans.
  • MANAGEMENT: Chemical control if damage threshold is met.


  • SYMPTOMS: Feeding, starting at the top, going downward, can cause complete defoliation. Feeding starts on tender leaves, gradually move to older leaves, and when foliage is removed, they attack tender stems, buds, and small bean pods.
  • TIME OF ATTACK: Late season in the South.
  • CONDITIONS FAVORING: Worms emerge any time during the season.
  • MANAGEMENT: Natural enemies; chemical control when threshold is met.
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