There are several Tomicus species that feed on various conifers. Many
are familiar with Tomicus piniperda, the common pine shoot beetle,
since it was identified near Cleveland, Ohio in 1992. Two other species,
T. minor and T. destruens, are not known to be present in the United
States. Probable introduction pathways include: unprocessed logs,
fire wood, tree trimmings, and lumber with the bark still attached.
Pines are the most common host, although T. piniperda may attack fir,
larch, or Douglas fir. T. minor has also been reported on larch. Both T.
piniperda and T. minor have one generation per year. For T. destruens,
two to three overlapping generations per year are suspected; however,
current theories suggest they may actually be multiple broods resulting
from mated females attacking multiple trees. After mating, females
construct egg galleries within the inner bark and outer sapwood. Eggs
are pearly white. After hatching, larvae construct feeding galleries. Larvae
are white, c-shaped, legless grubs with an amber colored head capsule
which may be as long as 1/8 inch when mature. Pupation can occur, in
cells, at the end of the larval galleries or in the bark. Pupae are white
with some adult features, including rudimentary wings. Adults emerge
and feed by boring into tender pine shoots. This feeding may occur as
a mass attack on susceptible trees. Attacks are characterized by reddish-brown boring dust on the bark surface of trees and, if relatively
vigorous trees are attacked, conspicuous pitch tubes on the bark surface.
Reddening or browning of shoots is also common. Adults are darkbrown,
elongate and about 3/16 inch in length. The ends of the wing
covers bear features to distinguish between the various species. The
head is visible, when viewed from above, and has six-segmented red-yellow
antennal clubs. Blue stain fungi or other vascular wilts are
commonly associated with these beetles.