Barley straw fly

The barley straw fly (Tetramesa hordei) belongs to the family Eurytomidae, order Hymenoptera. It is a specialized pest that impacts barley production by causing the formation of galls in the stems of the plant. Unlike many leaf-feeding insects, this species completes its entire larval stage hidden within the plant tissue.

The primary host for this pest is barley (Hordeum vulgare), though it can occasionally affect other small grains. The larvae feed on the internal tissues of the stem, effectively acting as a nutrient sink. This feeding behavior disrupts the vascular system, preventing the efficient translocation of nutrients to the developing spike during the grain-filling stage.

The life cycle begins with overwintering larvae residing inside the stubble left in the field after harvest. As temperatures rise in spring, the insects pupate and emerge as adults. After mating, the females use their ovipositors to insert eggs into young barley stems, initiating a new generation that will continue to develop inside the host plant.

Infestation symptoms include localized swelling or galls on the stem nodes or internodes. These deformations make the stems structurally weak, leading to lodging and reduced grain yield. Because the larvae are protected inside the stem for most of their life, they are largely unaffected by external chemical sprays, making preventative agronomic practices crucial.

Management strategies for the barley straw fly focus on cultural control and sanitation to break the life cycle:

• Deep plowing or soil inversion after harvest to bury infested stubble and kill overwintering larvae.
• Implementing effective crop rotation to reduce local populations of the pest over time.
• Control of volunteer cereals and related grasses that may serve as alternative hosts between seasons.
• Selecting resistant barley varieties that show lower rates of infestation under field conditions.