New Introduction - Common Pine Shoot
Beetle, Tomicus piniperda
Figure 1.Adult Beetle
The common (or larger) pine shoot beetle, Tomicus
(=Blastophagus) piniperda (L.), was discovered near Cleveland,
Ohio in July 1992. As of this writing, it is now in six states: Illinois,
Indiana, Michigan, New York, Ohio, and Pennsylvania. Adults of the common pine
shoot beetle are cylindrical and range from 3 to 5 mm in length (about the size
of a match head). Their head and thorax are shiny black while the wing covers
are reddish-brown to black. Eggs are 1 mm long, oval, smooth, and shiny white.
Larvae are legless, slightly curved, have a white body and brown head, and can
reach 1/4 inch (5 mm) in length when fully grown.
Figure 2. Mined shoots os
Scotch Pine. (Arrow indicates entrance gallery)
Tomicus piniperda completes one generation per year throughout its
native range of Europe and Asia. Overwintering adults initiate flight on the
first warm (50-54° F) days of spring which probably occurs in February or
March in the Lake States in the northeastern United States. Adults quickly
colonize either recently cut pine stumps, logs, or, at times, infest the trunks
of severely weakened trees. If necessary, adults can fly ½ mile (1 km) or
more in search of host material. Pine is the principal host tree. When
populations are high, adults may breed in spruce, fir, and larch logs that
occur in stands mixed with pine. Various species of blue stain fungi are
associated with this bark beetle.
Adults use host volatiles such as
alpha-pinene to locate suitable host material for breeding. T. piniperda
does not appear to produce an aggregation pheromone (sex attractant). Females
initiate gallery systems and soon one male joins each female. After mating,
females construct individual vertical egg galleries within the inner bark and
outer sapwood. Egg galleries extend 4 to 10 inches (10 - 25 cm) in length.
Females lay eggs singly in niches that are cut into both sides of the egg
gallery. After hatching, larvae construct horizontal feeding galleries that are
1.5 to 3.5 inches (4 - 9 cm) long. Most larvae complete development, pupate,
and transform to adults in May and June.
Figure 3. Damaged shoots
on Scotch Pine.
The newly formed adults tunnel through the outer bark, creating circular exit
holes about 2mm in diameter. They then fly to the crowns of living, healthy
pine trees of all ages, but prefer the taller trees in any particular area.
Adults feed primarily inside lateral shoots, mostly in the upper half of the
crown from May through October. During this period of maturation-feeding, each
adult may destroy 1 to 6 shoots. Scotch pine is preferred, but other pine
species have been infested in the Lake States including Austrian pine, eastern
white pine, red pine, and jack pine.
Adults usually enter shoots in the
one-year old or current year's growth. Normally, one beetle infests each shoot.
They tunnel into the center and bore outwards, hollowing out 1 to 4 inches of
the shoot. After several weeks, adults often emerge and enter other shoots.
Infested shoots generally bend near the point where the beetles entered, turn
yellow to red, eventually break off, and fall to the ground.
In the Lake States, adults exit twigs soon after the first frosts in
October and November and enter the thick bark at the base of pine trees to
spend the winter. Adults typically overwinter at the base of the same pine tree
that supported their maturation feeding. A few beetles may pass the winter
inside twigs in the crown.
The most severe damage caused by T. piniperda is the destruction of
shoots during maturation feeding. When shoot feeding is severe, tree height and
diameter growth are reduced.
Generally, the reproduction phase of this beetle in pine stumps and slash
causes little economic damage. However, in China and Poland, T.
piniperda has attacked and killed apparently healthy pine trees.
For more information:
- Bob Haack USDA FS NCFES
- Dan Kucera USDA FS NA
- Steven Passoa USDA/APHIS/PPQ
USDA Forest Service
State and Private Forestry
Forest Health Protection