Tree infestation can be detected by looking for exit holes 3/8 to 3/4 inches in diameter (1–2 cm) often in the larger branches of the crowns of infested trees. Sometimes sap can be seen oozing from the exit holes with coarse sawdust or "frass" in evidence on the ground or lower branches. Dead and dying tree limbs or branches and yellowing leaves when there has been no drought also indicate "A. glabripennis" infestation. Traps can also be used containing a pheromone and a plant kairomone to attract nearby adults. Some acoustic sensors can also differentiate larval feeding within trees. Dogs can also be trained to detect the smell of frass on trees.