Insects & Diseases

Most forest insects and pathogens in the Southwest are naturally occurring components of ecosystems and play an important role in dynamic processes. They affect short- and long-term vegetative structural diversity, provide food and habitat for animals, and contribute to biological diversity. These organisms, along with fire, are among the major disturbance agents in the Southwest. Outbreaks of forest insects and diseases can result in shifts in forest composition and structure. The degree of shift depends upon the particular insect and/or disease and on the condition of the ecosystem affected.

The actions of insects are often easily observed as their populations can quickly expand under favorable climatic conditions. Some insects are significant natural disturbance agents, capable of altering forest succession. For example, bark beetle populations can increase dramatically under drought conditions and cause large-scale tree mortality. In contrast, indigenous tree pathogens increase gradually and their presence and effects may go relatively unnoticed. Although most people see dwarf mistletoe in our forests, few realize that it is the primary agent of growth loss and will gradually kill trees. Insects and pathogens often interact, as is seen when bark beetles target diseased trees.

Please refer to your local Forest Service, Forest Health zone office, State Forest Health Specialist, Cooperative Extension Agent, or State Forester for information concerning specific control measures.

Specimen Identification

Federal land managers sending insect or disease samples to us for identification should include a specimen label (PDF, 142 kb) with their shipment. Additionally, please see our packing tips (PDF, 19 kb).

Tree Risk Evaluation

Federal land managers can use the tree risk assessment form (PDF, 154 kb) for their tree evaluations.


Insect & Disease Surveys

Learn about our aerial detection surveys are conducted and view reports.

Bark Beetles

Bark beetles in Arizona and New Mexico.


Weed Management

Field guides for weed management in the Southwest.


Listing of forest health publications and access to on-line versions.