What's eating my bitternut hickory?

Bitternut hickory nuts are too bitter for most wildlife but squirrels still cache them. The tree is more susceptible to hickory bark beetle than the sweeter-nutted species, especially on poorly drained or drought-stressed sites. Fall webworm and hickory shuckworm affect foliage and husks annually. The species has no significant edible nut pest pressure because wildlife largely avoids the bitter kernel.

Beetles mass-attack stressed trees, boring through bark to create winding egg galleries; infected trees show branch dieback, yellowing foliage, and circular entry holes with sawdust frass. Keep trees vigorous through proper siting (well-drained soil), mulching, and supplemental watering in drought; remove and chip infested wood; no curative chemical spray exists once beetles are established inside.

Silken tent nests at shoot tips house large colonies of hairy caterpillars; foliage within webs is consumed; multiple generations can cause repeated mid-to-late-summer defoliation. Prune out and destroy tents before larvae disperse; Bt or spinosad for persistent pressure; avoid broad-spectrum insecticides that eliminate natural parasitic wasp populations.

Larvae bore through the thin, bitter husk; because the nut itself is unpalatable, crop economic loss is nil, but repeated husk damage weakens the tree's reproductive output. No treatment warranted for non-crop trees; for ornamental or silvicultural specimens, a single spinosad spray at peak adult flight in June is sufficient.