Heavy infestations of holly leafminer may result in every leaf on a plant being mined. This may cause plants to drop many leaves, which reduces the plant s aesthetic appearance until new growth begins next spring. There is one generation per year.
Adult females are present shortly after new leaves develop on plants.
They can emerge over a 6-week period in the spring. The female lays eggs into the leaves in early to late spring. The eggs are normally laid on leaf undersides and in the midvein of individual leaves. Females pierce the leaf epidermis with their sharp ovipositor and then insert an egg into the mesophyll layer of the leaf. Egg laying can create a noticeable green blister on the leaf.