This time of year in Southwest Colorado, you might notice a loud and droning buzzing or clicking sound in the tree canopy above you. Don't worry, it's not the spruce beetle or mountain pine beetle savagely attacking your trees. It's more than likely cicadas.

Cicadas have large protruding eyes and veiny transparent wings. Although cicadas are abundant, they are much more often heard than seen. Male cicadas have a pair of drumlike organs on the sides of their abdomen that they contract and release to make a sound to attract females.

You won't notice cicadas every summer. The nymphs spend two to five years developing underground before emerging from the soil. Adults are present for four to six weeks after they've emerged. A cicada sometimes is called a locust, which is a migratory grasshopper.

Cicadas cause little or no harm to plants and generally do not require any control. Occasionally large numbers of certain cicadas, like a common southwest Colorado species the Putnam's cicada, can cause minor injury to trees and shrubs when they lay their eggs in the stems. In this case small splits can be seen in the surface of the bark, particularly on trees such as maple, crabapple and honeylocust.

For more information on forest insects, visit www.csfs.colostate.edu or contact the Colorado State Forest Service Durango District at (970) 247-5250.