A female emerald ash borer feeds on leaves and will soon deposit eggs on the bark of an ash tree.
A female ash borer ready to lay eggs
The adult borers eat ash leaves before they lay eggs on the bark.
The borer larvae make wandering galleries in the cambium, xylem and phloem. This is what kills the tree.
In spring, the adult beetles emerge by tunneling through the bark, leaving little piles of sawdust.
The adults emerge from the stem, making a characteristic D-shaped exit hole.
The borer begins at the top of the tree and works its way down, sometimes taking several years to kill the tree.
When the beetle is done, cities and forests alike are left with dead trees.