Summer Insect Concerns in Faba Beans

Overwhelmingly, Faba beans are grown for the human food/food processing market in Manitoba. As a result, both yield and quality of the harvest become very important. Two summer insect pests are a particular threat. Let’s take a quick look:

Pea Aphids

• Scout for pea aphids from the end of July to mid-August.
• Aphids often hide under the leaves and cluster in areas of new growth.
• The economic threshold for pea aphids in faba beans is 34–50 aphids/main stem and provides a seven-day lead time before aphid populations reach the economic injury level of 96–142 aphids/main stem.
• Click Here for More on Pea Aphid in Faba From SPG
• Click Here for Faba Bean Insect Management Chart – Guide to Field Crop Protection 2025. 

Lygus Bugs

• Lygus bugs do not generally limit yield, but they are a concern for seed quality and grading.
• They pierce pods, leaving behind dark sunken areas on the seed from enzymes in their saliva.
• Fabas require less than 1% perforated damage to be graded No. 1 Canada.
• Monitor fields during pod development for lygus until seeds in the pod become firm.
• Starting at early podding, visit five locations conducting 10–25 sweeps during the warm, sunny part of the day when lygus are most active. Count adult and late instar nymphs (nymphs have five black dots on their backs).
• Economic thresholds are not established for faba beans, but research suggests a low threshold – as few as five lygus per 10 sweeps during early pod stages.
• Discuss lygus bug control and control threshold levels with your contracted buyer or potential buyers. Examine your production contract to understand your obligations regarding lygus bug control and how lygus bug perforated damage is being evaluated.
• Click Here for More on Lygus Bug in Faba Bean from SPG
• Click Here for Faba Bean Insect Management Chart – Guide to Field Crop Protection 2025