Insect Pests of Conifers

Coniferous forests carry their own unique threats, including both native and nonnative insects.  Many of these insects have been present in the United States for decades.  Their inherently cyclic emergence cause periods of regional concern and play a vital role in shaping forest structure. They generally attack individual weakened or severely stressed trees. Large infestations develop only occasionally, usually in the aftermath of widespread environmental stress such as drought, storm damage, or wildfire. Overall, their action served to thin forests, reducing competition, leaving the stronger trees, and decreasing the risk of severe outbreaks.

It is important to understand the physiology and history of these conifer- and hardwood-infesting insects to inact proper management when invasions occur.  For example, pine beetles often begin their attack on tree boles where as hemlock woolly adelgids show their first signs of infestation on the underside of branches.  Some insects, such as the Nantucket pine tip moth and the Texas leaf-cutting ant, attack mainly seedlings and saplings whereas others may attack older weakened conifers. The baldcypress leafroller tends to damage pole-sized to small sawtimber-sized baldcypress trees in higher quantities than younger or older trees. Knowledge of these and other differences are both interesting and imperative in understanding severity and urgency when dealing with insect infestations.

In this section, more detail is provided about 5 species of pine bark beetles, including the southern pine beetle. The other bark beetles discussed include the black turpentine beetle, small southern pine engraver, southern pine engraver, and six-spined engraver. Information is also provided for both the hemlock and balsam woolly adelgids, native pine weevils, Nantucket pine tip moth, baldcypress leafroller, Texas leaf-cutting ant, and pine sawflies.