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Emerald Ash Borer Life Cycle

Larvae (immature form)

After hatching, larvae bore through bark to feed on ash trees' vascular tissue which transports water and nutrients throughout the tree.
Growing larvae zigzag through this delicate tree tissue as they feed, forming S-shaped tunnels that are flat and wide. These tunnels are packed with frass (excrement).
Mature larvae are about 1 inch long; they are creamy white with a flat and broad-shaped body.
Larvae spend the winter under bark.

Three different stages of EAB larvae.

(D. Cappaert, MSU)

Larval EAB feeding on an ash tree's vascular tissue.

(J. Ellis, Purdue University)

Larval EAB leave s-shaped feeding tunnels behind as they feed under ash bark.

(Ed Czerwinski, Ontario Ministry of Natural Resources)