Buds and Shoot Insects

Pine Tip Moths
Rhyacionia spp.

Host:  Ponderosa pine

Figure 158. Figure 158. Adult pine tip moth.

Symptoms/Signs:  Insect appearance varies between species. R. bushnelli adults have a wingspread of 10 to 15 mm; forewings are mottled yellowish gray and reddish brown. Larvae are yellowish with black heads, and about 9 to 12 mm long when mature. R. neomexicana adults have a wingspan of about 24 mm. Forewings are irregularly banded with transverse bars of dark gray, blackish and brick-red scales on the inner two-thirds of the wing. Larvae are usually orange in color with dark brown to light tan head capsules and are about 12 to 16 mm long when fully developed.

Figure 159. Figure 159. Damage of ponderosa pine shoot caused by pine tip moths.

Biology:  Larvae mine inside new shoots in spring and early summer, killing them. Both lateral and terminal shoots are attacked. Larvae initially mine needles and then bore into the shoot. Pitch tents, frass, and silk webbing are all signs of tip moth activity. Once in the shoots, larvae feed between the pith and the bark, eventually hollowing out the shoot.

Effects:  Larvae mine in the phloem and xylem of lateral and sometimes terminal shoots. Small trees, those less than 2 m tall are most susceptible. Shoots are killed by the attacks. Repeated attacks slow growth and cause crooks, forks, multiple stems, and spike tops. Tip moths rarely kill established trees outright, but attacks can affect survival of young planted seedlings.

Similar Insects and Diseases:  See Western pines shoot borer and ponderosa pitch nodule moth..

References:  24, 44

Figure 160. Figure 160. Closeup of damaged ponderosa pine shoot caused by pine tip moths.