Winter is spent as a prepupa in topsoil or duff. Adults emerge in early spring and lay eggs in slits in current or previous years' needles. Eggs hatch in 4 to 5 weeks. A range of larval age groups may be present throughout the summer. Young larvae feed on the edges of needles, leaving a central spine, but large larvae consume entire needles.
Damage tends to be worse in years with warm, extended falls.
From July through September, larvae reach maturity and drop to the soil to overwinter. Young or stressed trees are preferred, and small ornamental pines may be completely defoliated and killed in heavy infestations. Trees that are growing in poor sites or under stress are attacked more readily than healthy trees. Damage can sometimes be reduced by getting rid of competing vegetation, planting in high-quality sites, and promoting early closure by close plantings. If infestations are light, manual removal of larvae may effectively control the pest.