Azalea Leafminer
Caloptilia azaleella(Brants) Gracillariidae, LEPIDOPTERA


DESCRIPTION

Adult - The adult azalea leafminer is a small, yellow moth with purplish markings on the wings. The wingspan is about 10 to 13 mm.

Larva-The leaf-mining larva is yellowish and about 13 mm long. It has three pairs of prolegs found on abdominal segments three, four, and five. The proleg hooks (crochets) are singly arranged in a U-shaped pattern (penellipse) with a series of crochets within the pen.


BIOLOGY

Distribution -The azalea leafminer is found in most states where azaleas are grown.

Host Plants - Azaleas are the only known hosts for this insect.

Damage - This leafminer larva has little effect on plants grown outdoors, but it may do considerable damage to cuttings in the greenhouse. Mining within the leaf, the young larva causes the formation of brown blisters on the leaf surfaces (Color Plate IF). As the larva matures, it emerges and rolls the edge of a leaf around itself for protection while feeding on the leaf surface. Seriously injured leaves usually turn yellow and drop, thereby causing an unslightly plant.

Life History - This leafminer larva has little effect on plants grown outdoors, but it may do considerable damage to cuttings in the greenhouse. Mining within the leaf, the young larva causes the formation of brown blisters on the leaf surfaces (Color Plate IF). As the larva matures, it emerges and rolls the edge of a leaf around itself for protection while feeding on the leaf surface. Seriously injured leaves usually turn yellow and drop, thereby causing an unslightly plant. Life History—Eggs are deposited singly on the undersides of leaves along the midribs, usually one to five per leaf. The young (larvae) hatch in about 4 days, mine into the leaves, and feed inside them. At this stage, the leaves appear to have blisters. If a leaf is held up to the light, the larva can be seen inside. When about one-third grown, the larva emerges, moves to the tip of a new leaf, and rolls it up for protection while feeding and growing. When nearly grown, the larva rolls up the margin of a leaf and spins a cocoon inside. The moth emerges from the cocoon, mates, and deposits eggs for another generation. Under greenhouse conditions, the larvae may be found at any time during the year. The insect overwinters outdoors as a larva or pupa. Adults appear and females begin to lay eggs about the time plants bloom in the spring.


CONTROL

Because the larva protects itself by mining into and rolling the leaf, this insect is not easy to control. Several insecticide-spray mixtures have yielded satisfactory control when applied at the first sign either of the adult moth or of foliar injury by the larva. One or two applications, 1 to 2 weeks apart, are usually sufficient. For specific chemical controls, see the current state extension service recommendations.

Return to AG-189 Table of Contents