Apple Blotch Leafminer: Appearance, Territory, Damage and Life Cycle

Latin Name: Phyllonorycter

Appearance: The apple blotch leaf miner (ABLM), Phyllonorycter Crataegella, is the most common gracillariid leafminer found in commercial apples. Until recently, the ABLM was thought to be a minor pest. However, multiple major outbreaks have been documented since 1973.

Hosts Plants: Apple blotch leafminer and spotted tentiform leafminer prefer apple leaves and can be seen on apple, pear, cherry, plum, and quince.

Territory: North America specially Canada

Damage Insect Cause: The first three larval instars feed on tissue between the leaf’s two epidermal layers, resulting in a translucent sap feeding’ mine visible only from the underside of the leaf surface. The last two instars feed more extensively on leaf tissues, and their ’tissue feeding’ mines may be seen from both the top and bottom of the leaves. Numerous white spots may be found on the top leaf surface of the ’tissue feeding’ mine.

Life History and Habits: The apple blotch leaf miner hibernate as pupae in mines on fallen leaves over the winter. Adults emerge in late April to early May and deposit eggs on the undersides of leaves in a single layer. When the wings are folded, the adults are 3/16-inch length light brown moths with white spots that resemble transverse bands. ABLM is nearly identical to STLM, with the exception of smaller forewings that are less heavily marked with white scales. In 5-16 days, the eggs hatch and feed as “sap feeders” just beneath the lower leaf epidermis. In late May, larvae begin eating just under the upper leaf epidermis, causing heavily speckled mines to appear on the upper leaf surface. Every year, three generations are born.