Dock bug

The dock bug (Coreus marginatus) is a true bug belonging to the order Hemiptera and the family Coreidae. These insects are easily recognizable by their shield-like shape, brown coloration, and distinctively expanded edges of the abdomen. Adult dock bugs typically reach a length of about 10–15 mm and possess a robust appearance that helps them blend into decaying plant matter.

As a polyphagous pest, the dock bug targets a variety of plants, showing a strong preference for species within the Polygonaceae family, such as docks (Rumex) and rhubarb. They also frequently attack strawberries and various ornamental shrubs. By piercing the plant tissues with their specialized mouthparts, they extract essential sap, which directly impacts the vitality and growth of the host plant.

The biological cycle of this species is characterized by a single generation per year. Adults hibernate throughout the winter in sheltered areas such as leaf litter, hedgerows, or soil debris. As spring temperatures rise, they emerge to feed and begin the mating process. Eggs are laid in clusters on the undersides of leaves, and the nymphs undergo five developmental stages before reaching adulthood.

Damage caused by the dock bug is often visible as chlorotic spots, stunted growth, and distorted foliage. In fruit crops like strawberries, feeding can cause localized necrosis on the berries, making them unmarketable. Because the bug injects salivary enzymes during feeding, the plant often suffers from metabolic disruption, which can stunt its development during the critical growth phase.

Effective management strategies combine cultural and chemical approaches to maintain pest populations below economic thresholds. Essential practices include:

• Maintaining field hygiene by removing alternative host weeds.
• Tilling the soil in late autumn to expose overwintering sites.
• Manual removal of adults where infestations are localized.
• Utilizing targeted insecticide applications only when monitoring indicates a significant population increase.