Eggs are scalelike, flattened oval in shape, and similar in appearance to codling moth eggs. Filbertworm eggs are white when newly laid, turning darker as hatching approaches. Larvae overwinter in organic matter or soil, can reach 0.5 inch (1.3 cm) in length, and range from beige to pink with a dark brown to black head. Pupation occurs in a silk cocoon the next spring. One generation with a partial second has been observed in cool areas such as Oregon. However, in warm areas of California two generations per year is probable with second generation adults appearing in the fall.