Pest Photo

Mark Schwarzlander, University of Idaho,

St. johnswort borer

Agrilus hyperici

St. johnswort borer (Agrilus hyperici) is a beneficial insect. It is a native of Europe and was first detected in California in 1950.

This is an important biocontrol for St. John'swort. When the larvae is feeding within a root of a plant, it can entirely consume the tissues, severely damaging the plant. Flower production is reduced because stems produced from an infested root crown are stunted. Most infested plants are killed.