Currant bark midge

The currant bark midge (Resseliella ribis) is a small dipteran insect belonging to the Cecidomyiidae family. It is a highly specialized pest that primarily targets black and red currant bushes, causing significant damage by feeding under the bark of young shoots and stems.

The biology of this pest involves an active adult stage during the blooming period of currant plants. Females deposit their eggs into natural cracks or wounds in the bark of developing shoots. Once hatched, the larvae feed gregariously on the cambium and phloem layers, which eventually destroys the plant's vascular tissue.

The life cycle typically includes multiple generations per growing season. Larvae from the final generation drop to the soil, where they spin cocoons to overwinter. As temperatures rise in the spring, the larvae pupate, and the adults emerge to start a new cycle of infestation in the plantation.

The damage caused by the midge is often insidious. Bark over the feeding sites turns dark, becomes depressed, and cracks open. This damage hinders nutrient transport, leading to the sudden wilting and dieback of branches. Fungal pathogens often enter through these feeding sites, further worsening the condition of the shrub.

Effective management strategies require a multi-faceted approach:

• Prompt pruning and burning of all infested stems to eliminate larvae before they exit to the soil.
• Applying ground covers or mulches to prevent adults from emerging from the soil in spring.
• Timed insecticide applications during the adult emergence and egg-laying period.
• Maintaining plant vigor to help shrubs withstand minor infestations.
• Cultivating the soil around the base of bushes in autumn to disrupt overwintering cocoons.