Damage:

Linear (serpentine) mines are found just beneath the upper surface of the leaf.  Mines are about 2 inches (5 cm) and 1/23 (2 mm) wide, whitish to light tan, with a line of black frass in the center.  Mine are found in cells with chlorophyll.  If the egg is laid near the center of the leaflet, the early bends of the resulting mine may lay around each other in a spiral because the larvae are unable to cross leaflet veins.  If the egg is laid near the margin of the leaf, the mines will

Seasonal History:

In late April to early May, female moths lay minute, flat, oval, shiny eggs on the upper surface of the foliage.  Pale-yellow larvae about 1 mm long hatch and enter the leaf. Mature larvae are light-green in color and about 5 mm long.  When development is complete, each larva cuts a crescent-shaped slit in the upper surface of the leaf at the end of its mine, crawls out, drops to the ground, and pupates in ground litter (light tan to reddish brown, foot-shaped cocoon). A small purple and white moth emerges within a week.  There are four generations per summer. 

When to Control:

Apply leaf miner controls when an average of 1 mine per leaflet on 5 leaflets per compound leaf are observed in 50% of the leaves sampled or when damage is rated medium.  Spot treatments of orchards may be necessary.