Flax gall midge

Taxonomy. The flax gall midge (Contarinia kanervoi) belongs to the order Diptera and the family Cecidomyiidae. It is an economically significant pest specifically associated with the genus Linum, often causing localized but severe outbreaks in flax fields.

Host plants. This midge primarily affects flax (Linum usitatissimum), targeting both fiber flax and oilseed flax varieties. It is considered a specialized pest that can significantly impact yields in areas with intensive cultivation.

Biology and life cycle. The adult flies emerge during the budding stage of the flax plant. Eggs are deposited into the flower buds or apical shoots. Larvae develop inside the plant tissues, feeding on sap and causing hypertrophy, which creates the characteristic gall-like swellings. The insect overwinters as a larva or pupa in the soil, which helps it survive harsh winter conditions.

Damage and economic impact. Infested plants show stunted growth, distorted stems, and failed bud development. If the midge affects the terminal bud, it stops the vertical growth of the plant. This leads to a substantial loss in fiber quality and seed production, as the flowers are destroyed before pollination occurs.

Management strategies. Effective control measures focus on integrated pest management (IPM):

• Crop rotation is essential to break the life cycle.
• Deep plowing in autumn significantly reduces the overwintering pupae population.
• Monitoring of flight periods using traps to determine the timing of insecticide application.
• Selection of early-maturing varieties to escape the peak infestation window.