Probably no other insect is of more concern to managers of southern pine
forests than the southern pine beetle. Loblolly and shortleaf pine seem
to be preferred hosts, but all of the southern pines may be attacked
wherever they occur in North and Central America.
Adult beetles are about the size of a grain of rice, stout and
reddish-brown in color. While they commonly attack lightning-struck or
weakened trees, they can also quickly build up to high populations
capable of successfully attacking healthy trees during periods favorable
to their development. Adult beetles bore directly through the bark,
mate, and the females begin to excavate S-shaped egg galleries in the
inner bark. Eggs are deposited in niches on either side of these
galleries and hatch into small legless grubs within four to nine days.
The grubs mine for a short distance before boring into the outer bark
where they pupate. There are from three to seven generations per year
depending on locality and weather. Drought seems to be associated with
major outbreaks of this insect.
[Illustration: Adults of the black turpentine beetle, the southern
pine beetle and three species of _Ips_ engraver beetles.]
Control includes rapid salvage and utilization of infested trees and
piling and burning of infested material. Outbreaks usually subside with
the advent of unfavorable weather and improved host vigor.
[Illustration: Southern pine beetle larval galleries.]
[Illustration: Southern pine beetle pitch tubes.]
IPS ENGRAVER BEETLES, _Ips_ spp.
With the possible exception of the southern pine beetle, no other
insects cause as much mortality to southern pine forests as do the three
species of _Ips_ engravers. Usually they attack severely weakened trees,
lightning-struck trees, or fresh slash left by logging operations.
During drought periods they can successfully attack otherwise healthy
pines.
[Illustration: Pine showing typical symptoms of _Ips_ attack.]
Attacked trees are quickly girdled by the adults as they construct their
egg galleries in the inner bark. Death is usually hastened by the
introduction of blue-stain fungi which blocks the flow of sap. Small
reddish pitch tubes are frequently the first sign of attack, but they
are usually absent in trees suffering from drought. Peeling back the
bark of an infested tree will reveal typical Y- or H-shaped egg
galleries with short larval galleries extending perpendicular to them on
either side. _Ips_ beetles are easily recognized by their “scooped out”
posteriors which are surrounded by varying numbers of tooth-like
projections. It takes only 18-25 days to complete one generation,
allowing populations of these beetles to increase very rapidly during
favorable conditions.
At present the best control is the speedy removal and utilization of
actively infested trees, making sure that the bark and slabs are
destroyed.