Cottonwood Borer (Plectrodera scalator) - The cottonwood borer is a common wood borer of cottonwood and poplars and infests the bases and roots of living trees. The insect is widely distributed throughout the eastern United States and the Midwest; however, it is most common in the Great Plains from Texas to South Dakota and throughout the Mississippi River Valley. Within Colorado, the cottonwood borer is restricted to the southeastern portion of the state. The adult is an elongate, robust, strikingly patterned beetle that is approximately 1-1 3/4 inches (2.5-4.4 cm) long and 1/2 inch wide. Mature larvae are approximately 2 inches long, and the pupa is approximately 1 1/2 inches long.