Tyrpophloeus populi is a species of bark beetle that have been suggested as the cause of sudden aspen decline. It was first described by the American entomologist Andrew Delmar Hopkins. Bark beetles have been reported to have lengths ranging from 1.7 to 2.1 millimeters, with their length approximately 2.3 times as long as they are wide. They come in black and dark brown body colors. Tyrpophloeus populi has been found throughout North America, from East Nevada and North Arizona to Saskatchewan and New Brunswick.