Insect Stressors

Forest health is often stressed by both native and nonnative insect populations. Southern trees are hosts for a variety of insects. Although most insects are vital to maintaining ecosystem functions, several species have been introduced from Europe and Asia and, due to a lack of natural endemic controls, have threatened the survival of several southern tree populations. Factors such as fire suppression, drought, and air pollution also influence periodical outbreaks of native insects causing tree mortality. The damage by insect pests impact forest by stressing and killing trees which can lead to increased fire risks, reduction in wildlife habitat, loss of timber resources, endangerment of rare species, loss of biodiversity, and promotion of invasive plants from increases in disturbance and light availability to the understory environment.

Of the several types of forest stressors highlighted in the encyclopedia of Southern Forest Science, including diseases, exotic and invasive plant species, and a host of abiotic stressors, insects often receive a higher amount of attention from the general public due to their visibility and tangibility.  Many people are familiar with the southern pine beetle or the hemlock woolly adelgid.  However, there are many more less-familiar pests that also threaten our southern forests.

In this section, eighteen insect stressors affecting coniferous and hardwood forests are looked at in more depth.  Special attention is given to the southern pine beetle, which represents one of the most serious forest health hazards.