Oak Shothole Leafminer: Appearance, Territory, Damage and Life Cycle

Latin Name: Agromyza Viridula

Appearance: The oak Shothole leafminer is a tiny insect in the Agromyzidae family. Although it is a fairly short-lived species, there is not much information about them. They are found Eastern US.

Hosts Plants: Black oak, Burr oak, Chinese chestnut, Post oak, red oak, Sand post oak, Scrub oak, Turkey oak, and White oak.

Territory: Although nothing is known about the oak Shothole leafminer or other agromyzid leaf miners, it is assumed to be native to the United States. It’s thought to be found all throughout the eastern United States, from Maine to Georgia, and most likely the whole eastern half.

Damage Insect Cause: The oak Shothole leafminer causes two forms of damage to the leaves: holes and dark brown “blotch mines.” Oak Shothole leafminer damage can limit photosynthesis to the point that oak seedlings cease growing for the season. Oak Shothole leafminer causes harm to full-grown trees, but if damage persists for several years, oak trees may exhibit more serious injury signs.

Life History and Habits: The oak Shothole leafminer, Japanagromyza Viridula, is a small fly that emerges in early spring to feed on oak leaf buds and young leaves. They feed by piercing the buds with their ovipositors (egg placers) and sucking the plant juice. When the buds break and new leaves sprout, a small hole forms at the oviposition injury location. The holes develop bigger (up to 3/8 inch) as the leaves expand. Females eventually pierce the leaves in order to lay their eggs. Tiny maggots hatch and excavate blotch mines as they grow.

Maggots leave their mines when they reach maturity, which is usually around the end of May, and descend to the ground to pupate and spend the rest of the summer and winter. When a mine is operating, it is bright green to brown, but when it is abandoned, it darkens. The wounded tissue breaks away over time, leaving large, jagged holes in the skin. For the rest of the growing season, female feeding holes and leaf mines will be present. Every year, a new generation is born.