Pine Tree Oozing Yellow Pitch: Dioryctria Moth Borer

Foamy Yellow Pitch on Pine Trunk = Dioryctria Moth

A 9-year-old pine in Fort Worth, TX, exudes a thick, light yellow, foam-like substance from the trunk.

Diagnosis

Dioryctria (pitch) moth borer. Larvae tunnel in the cambium, triggering massive pitch flow as a defense response. The "foam" is resin mixed with frass and air.

Damage Level

• Unsightly but rarely kills the tree.
• Can weaken branches, causing breakage.
• Multiple attacks over years may reduce vigor.

Control

• Spray trunk and scaffold limbs with permethrin (Onyx) or imidacloprid (Merit) in early spring (before adult flight) and again in mid-summer.
• Systemic soil drench (imidacloprid) also works but slower.
• Remove and destroy heavily infested branches.

Cultural Care

Water during drought, mulch, avoid wounding. Healthy pines resist borers better.