Azalea Leafminer: Appearance, Territory, Damage and Life Cycle

Latin Name: Caloptilia Azaleella

Appearance: Azalea leafminers are little yellow moths with purple patterns on their wings as adults. Their wingspan is around 12 inches. The leaf-mining stage is characterized by a yellowish caterpillar of about 12 inches in length. It possesses three pairs of prolegs, which are located on abdominal segments three, four, and five. Proleg hooks (crochets) are set individually in a U-shaped pattern, with a succession of crochets within the U.

Hosts Plants: Azaleas

Territory: This bug is a damaging pest of azaleas throughout its host area. It is native to Japan but has spread around the world. This species is widespread in the United States from Florida to Texas, and farther north to Long Island, New York, West Virginia, and the Ohio Valley. It is also found in northern California and the Pacific Northwest of the United States.

Damage Insect Cause: Azalea leafminers exclusively harm azaleas (Rhododendron spp.) and do so in two ways. Mines are light and scarcely noticeable when they are new, but as they mature, they produce brown blisters on the leaf surfaces. As the larva becomes older, it emerges from the leaf tissue and coils and binds the edge of a leaf around itself for protection. It continues to eat within the leaf, causing damage to the leaf tip. Seriously damaged leaves typically turn yellow and drop, resulting in an ugly plant. The leafminer larva has less of an impact on plants cultivated outside in North Carolina, but it can cause significant harm to azalea cuttings or plants grown in greenhouses.

Life History and Habits: Azaleas are the sole known host for the azalea leafminer, which may be found in practically every state where azaleas are grown. On average, one to five eggs are placed per leaf on the undersides of leaves near the midribs. The young hatch in about 4 days, mine into the leaves, and consume inside them. At this moment, the leaves appear to be blistered. If you hold a leaf up to the light, you can see the larvae within. The larva emerges when it is about one-third developed, goes to the tip of a new leaf, and wraps it for protection while eating and growing. When the larva has nearly completed its development, it rolls up the leaf’s edge and creates a nest.

The moth emerges from its cocoon, mates, and lays eggs for the next generation. Under greenhouse circumstances, larvae can be found at any time of year. The bug spends the winter as a larva or pupa outside. Around the time plants bloom in the spring, adults emerge and females deposit eggs.