Answer: Rose slugs are not true slugs but rather the larvae of the sawfly. These pests feed on the leaves, eating the soft tissues and leaving a "skeleton" of veins. Handpick and destroy any larvae you see. Insecticidal soap is effective against these pests; be sure to spray the undersides of the leaves where the larvae congregate. The rose midge adult is a tiny fly that lays her eggs in the leaf and flower buds. The eggs hatch into maggots, which burrow into the new growth causing the damage you see. When the maggots reach full size, they drop to the ground to pupate. In warm weather, the entire cycle from egg to adult can take just 10 to 12 days. To control rose midge, begin by regularly inspecting your plants; remove any infested shoots and destroy.Some people have had success detering the insects by planting alliums and other strong-smelling herbs. Insectides are targeted to the adult midges as they emerge from the soil--the tiny maggots that actually do the damage are inaccessible inside the buds. There are granulated pesticides that can be spread on the soil under rose bushes to intercept the emerging adult midges--check your local garden center. Read and follow label directions carefully.
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