Elm gall midge

Systematic position: The elm gall midge (Lat. Odinadiplosis) belongs to the order Diptera, family Cecidomyiidae. This insect is highly specialized and is known for forming galls on leaves of trees within the Ulmus genus.

Affected crops: The pest targets various elm species (Ulmus), commonly found in urban landscapes, parks, and natural wooded areas. It is particularly problematic for young trees that are more susceptible to leaf deformation.

Biology and life cycle: The insect overwinters as larvae in the soil or under leaf litter. In spring, as buds open, adults lay eggs on new leaf tissue. Once hatched, the larvae secrete substances that induce the host plant to form protective structures known as galls, where they live and feed until the pupal stage.

Nature of damage and pest status: The primary evidence of infestation is the presence of small, rounded, or blister-like galls on the leaves. Severe infestations can cause leaf curl, chlorosis, and premature leaf drop, which weakens the tree's vigor and significantly detracts from its ornamental value.

Control measures: Managing the elm gall midge is challenging because the larvae are protected inside the galls, rendering topical pesticides ineffective. Recommended management strategies include:

• Sanitary removal and destruction of fallen leaves in autumn to disrupt the pest's lifecycle.
• Applying systemic insecticides during the peak flight period of adult midges to prevent egg-laying.
• Implementing cultural practices to improve overall tree health, helping them tolerate minor infestations.