Hollyhock Stalk Borer: Identifying and Managing This Destructive Pest

Symptoms

A single stalk wilting, leaves curling and limp while neighboring plants are healthy suggests stalk borer (Papaipema nebris) infestation.

Diagnosis and Treatment

• Inspect stem for entry holes, frass (sawdust-like excrement).
• Cut open affected stalk—look for caterpillar inside.
• Remove and destroy infested stalks immediately.
• Contact your county extension office for approved insecticides and timing.

Prevention

• Remove weeds (especially ragweed, giant ragweed) that host borers.
• Clean up all hollyhock debris in fall.
• Rotate planting areas if possible.

Early detection saves the rest of your stand.