|Larvae removed from the crown of a dying blueberry bush|
|Prionus feeding damage to the crown of a blueberry bush|
The larvae reportedly take three to five years to mature, and may be more likely to occur on stressed bushes. Above-ground symptoms are hard to distinguish from drought stress or nutrient deficiency. Affected bushes are weakened progressively as the larvae grow and inflect more damage.
The only way to confirm the presence of these insects is to dig bushes and examine the roots and crown for damage or larvae. As pictured, the larvae are larger than most other grubs found in the root zone, are widest at the head end, with strong jaws, and with bodies that are elongated rather than the typical "C-shaped" grubs of other beetles.