Cereals: Hessian Fly

Excerpt from Agronomy Guide for Field Crops (Chapter 6)

Order OMAFRA Publication 811: Agronomy Guide for Field Crop

Table Of Contents

1. Description
2. Life History
3. Damage
4. Scouting Technique
5. Action Thresholds
6. Management Strategies
7. Updates on Cereals: Hessian Fly
8. Related links...

Description

Adult Hessian flies resemble small mosquitoes. They are smoky grey and fragile, and have pointed abdomens. The abdomen of the female fly is reddish, which is caused by the colour of the eggs developing inside. Adults are weak flyers and only live about 3 days.

Life History

Two generations occur per year. The Hessian fly overwinters as "flax seed" puparia in the base of old plant crowns. Adults emerge in the spring. Females lay their long, reddish eggs in rows on the upper surface of leaves of young winter wheat or volunteer wheat. Larvae develop and feed for approximately 3 weeks before forming a puparium in mid-June. A second generation emerges, and the insect continues its cycle until late September when it forms a puparium for overwintering.

Damage

Occurs both in the spring and fall. Larvae feed between the stem and leaf sheaths of the plant, causing the plant to turn dark bluish-green. Plants will become stunted and tough and eventually lodge. Heads may become bleached in colour. Risk factors include early-planted wheat and susceptible varieties.

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Scouting Technique

In the spring, scout fields when heads begin to fill. In the fall, begin scouting 3 weeks after wheat plants have emerged. Examine 20 plants in five locations across the field. Look for the "flax seed" puparia to determine the percentage of infestation.

Action Thresholds

None available.

Management Strategies

Delay planting of winter cereals until after the fly-free date. Refer to the section Planting Dates, for optimum seeding dates for your region. Destroy volunteer wheat and stubble before planting. Resistant varieties are available. No rescue treatments are available.

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Updates on Cereals: Hessian Fly

No updates available at this time.

Related links...

• Insects
• Cereals
• Field Crop Protection Guide - Publication 812

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