Leafminers of holly

Disease Information

Leafminers

Symptoms and damage

Leafminers (Phytomyza species) are common pests of hollies. the native holly leafminer (Phytomyzailicicola) is the most common. Leafminers are the larvae (immature forms) of small (about ?-inch in length) black and gray flies. The larvae are about 1 /16-inch long. The adult female inserts eggs into young leaves through puncture wounds made by her ovipositor. The presence of many punctures can result in deformed leaves. The eggs hatch in about four days. The larvae then tunnel through the leaf between the upper and lower surfaces. The paths they follow turn yellowish brown and typically broaden into a blotch. Their presence inside the leaf protects them from many insecticides. Parasitic wasps and birds are natural predators of these pests.

Management

With a light infestation, homeowners can handpick and destroy infested leaves. Foliar insecticides labeled for use by the homeowner include foliar systemic insecticides, such as acephate or spinosad for larvae within mines during May. As an alternative, a soil application of dinotefuran or imidacloprid is effective in controlling the larvae within the leaves. Treat shrubs with dinotefuran or imidacloprid in the early spring for season-long protection. Dinotefuran may move into shrubs more quickly than imidacloprid for faster pest control. Read and follow all label instructions and precautions



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