Soybean Insect
Identification and Management
Agent Training
June 26-27
NCSU and Plymouth, N
Plant Injury
Chewing
Piercing-sucking
Insect Mouthparts
Plant Injury
Gall making
Insect Vectors
Injury vs. Damage
Injury: harm or
destruction on the
host plant caused
by the pest
Damage:
measurable loss of
the host that affects
the yield quantity,
quality or
aesthetics
Old vs. New Injury
Old
New
Economic Injury Level
EIL: the lowest number of insects that causes economic
damage
EIL =
𝐶
𝑉𝐼𝐷𝐾
C = Cost of management per unit area
V = market value per unit of product
I = Injury units per insect per production unit; expressed
as a proportion
D = Damage per unit injury
K = proportionate reduction in potential injury or damage
Economic Threshold
ET = the number of insects that triggers a
management action
Corn Earworm/Tobacco Budworm
Thresholds now online!
www.nccrops.com
Will lead to Field Crop Entomology Webpage Link
Click Soybean Insect Pests
Click Corn Earworm
Click CEW Threshold Calculator for Soybeans
Sampling and Monitoring Methods
Direct Sampling
Transect
Random Sampling
Seedling Pests
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Thrips
Grasshopper/Katydid
Bean Leaf Beetle
Cutworm
Threecornered alfalfa hopper
Lesser cornstalk borer
Thrips
Tobacco thrips predominate after planting, then soybean thrips
Some Eastern flower thrips, very few Western flower thrips
White Margined Burrower Beetle
Grasshoppers
• Most common in reduced till
• Adults more difficult to kill
Katydid
Bean Leaf Beetle
Cutworm
Threecornered Alfalfa Hopper
Check when beans are less than 10 inches tall
Threshold is one per sweep
Threecornered Alfalfa Hopper Injury
Stem Borers
• Lesser cornstalk borer
• Dectes stem borer
Lesser Cornstalk Borer
Dectes Stem Borer
Vegetative/Flowering Stage Pests
(after seedling stage)
• Defoliators
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Corn earworm/tobacco budworm
Armyworm complex
Soybean looper (generally late-season)
Green cloverworm (generally NOT a pest)
Velvetbean caterpillar (generally late-season)
Bean leaf beetle
Japanese beetle
Blister beetle
Grape colapsis
Spider mites
Whitefly
Corn Earworm/Tobacco Budworm
Armyworm Complex
Armyworm Complex
Soybean Looper
Green Cloverworm
Generally NOT a pest
Velvetbean Caterpillar
Four pairs
of prolegs
Japanese Beetle
• Beetles often congregate
• Damage lacy
• Usually sub-economic
Blister Beetle
Grape Colaspis
Spider mites
Whitefly
Defoliator Thresholds
• Vegetative stages
– 30% defoliation
• Two weeks prior
to bloom and
during pod-fill
– 15% defoliation
Vegetative/Flowering Stage Pests
(after seedling stage)
Piercing sucking pests
–Kudzu bug
–Brown stink bug
–Green stink bug
Kudzu Bug
Kudzu Bug
Stink Bug Complex
Stink Bug Complex
Green Stink Bug Nymph
Brown Stink Bug Nymph
Piercing/sucking like Kudzu bug
However, stink bugs prefer and damage pods
Common Beneficial Insects
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Ladybird beetle
Lacewings
Minute pirate bug
Bigeyed bug
Nabids
Spined soldier bug
Praying mantis
Ladybird Beetle
eggs
adult
larva
Common NC ladybird beetles
Asian
pink spotted
pink spotted
Green Lacewing
adult
larva
eggs
Minute Pirate Bug
Bigeyed Bug
Nabis (damsel bug)
Spined Soldier Bug
Praying Mantis
Reproductive Stage Pests
• Defoliators
– Soybean looper
– Armyworm complex
– Bean leaf beetle
• Pod-feeders
– Corn earworm/tobacco budworm
– Stink bug complex
• Stem feeder
– kudzu bug
QUESTIONS?