Buds and Shoot Insects

Bark Moths
Dioryctria spp.

Pitch Moth
Synanthedon spp.

Hosts:  Piñon, ponderosa pine, and occasionally Douglas-fir and true fir

Figure 165. Figure 165. Damage to piñon caused by D. albovittella at Sunset Crater NP, Arizona.

Symptoms/Signs:  Pitch moth attacks appear as large masses of pitch that form at the wound site, but some species of Dioryctria can damage the cone or shoots. The pinyon twig moth, D. albovittella, can cause significant damage on young piņon. Bark moths typically produce less pitch.

Biology:  Pitch moths require 2 years for one generation to mature, overwintering as larvae each winter. Bark moths require only 1 year for a generation to mature, overwintering as eggs or larvae. Eggs are laid in bark crevices or near mechanical wounds on the bark. Newly hatched larvae tunnel under the bark forming

Figure 166. Figure 166. Damage caused by pitch moth.
irregular galleries or elongated gouges in the sapwood. Pitch moth larvae feed on pitch the tree produces in response to their tunneling. Oozing pitch masses 25 to 75 mm in diameter cover entry holes and conceal larvae and their destructive tunneling. Full-grown larvae are 15 to 25 mm long, dirty white, yellow, orange, green, or light brown. Bark moth larvae feed on the inner bark and when full grown, are marked with rows of dark spots.

Effects:  Larger branches, limbs, and trunks of young trees are attacked. Repeated attacks can seriously weaken and kill branches. The most severe damage is to trees under 6 m, especially in urban areas. The insects are rarely a problem on larger trees or in the forest environment.

Reference:  9