The poplar borer causes wet spots on the bark, black stain below entrance holes, and masses of frass (boring dust or shavings), mixed with sap near entrance holes in the bark and on the ground near the base of the tree. Their eggs are about 1/8″ long, creamy white color, usually laid singly, but sometimes groups of 2 or 3. Poplar borer larvae are round-headed wood borers, about 1 1/4″ long, legless, and white or yellowish, with a head that is thicker than the body. The pupae are about 1″ long, and yellowish white. Adult poplar borers are a long-horned beetle, 4/5″ to 1 1/8″ long, with a dark grayish blue body and brownish orange spots, and antenna that are almost as long as their body.