**Vine Stalk Borers** most commonly refers to **Moth Larvae** (e.g., *Synanthedon* spp. or other clearwing moths) or **Beetle Larvae** (e.g., *Ptilinus* spp.) that bore into the woody stalk or trunk of the vine. The conflict is **trunks and cordons destruction**: the larvae tunnel into the main permanent woody structure (the trunk, cordon, or permanent arms) of the vine, leading to structural instability, reduced nutrient flow, and often the death of the entire vine above the point of infestation. This is a severe long-term economic problem.
Taxonomy and Classification
This group includes borers from the Order Lepidoptera (Moths) and Coleoptera (Beetles). They undergo complete metamorphosis, often with a life cycle of 1-3 years within the woody tissue.
Physical Description
Larvae are 10 mm to 50 mm long.
- **Adult (Key ID):** Varies greatly, often moth species that mimic wasps or small, dark beetles.
- **Larva (Key ID):** Large, white, legless, grub-like larva with a brown head; found deep within the heartwood of the vine.
- **Damage ID (Key):** Piles of **frass** (sawdust) extruded from bore holes on the trunk; gradual dieback of entire arms/cordons; presence of large, weeping wounds (cankers) on the trunk.
- **Conflict:** Agricultural (Viticulture).
Distribution and Habitat
Found worldwide. Habitat is the woody tissue of the vine trunk, especially old or weak vines.
Behavior and Conflict
The conflict is their permanent damage to the vascular system.
- **Vascular Damage:** Tunneling directly interferes with the xylem and phloem, restricting the movement of water and nutrients, leading to vine decline.
- **Entry Points:** They commonly enter through poorly healed pruning wounds or damaged bark.
Management and Prevention
Management is **Trunk Protection and Sanitation**.
- **Sealing Pruning Wounds:** Applying fungicidal/insecticidal paint or sealant to large pruning cuts immediately after cutting.
- **Removal:** Removing and destroying heavily infested trunks.
- Application of a trunk wash (insecticide spray) to prevent adult females from laying eggs in bark crevices.
Conservation and Research
Research focuses on cultural controls and wound protection, as chemical control of the protected internal larva is often impractical or illegal on fruiting crops.