**Quince Sawflies** (often referring to species like *Hoplocampa testudinea*, which attacks pome fruits) are the larvae of a non-stinging wasp that causes damage to **quince, apple, and pear** fruit. The conflict is fruit contamination and loss: the female sawfly lays eggs inside the fruit, leaving a characteristic **crescent-shaped scar**. The larvae then tunnel just under the skin or deep into the core, causing the fruit to become rotten, drop prematurely, or be heavily scarred, rendering it unmarketable.
Taxonomy and Classification
Sawflies belong to the order Hymenoptera (Wasps, Bees, and Ants), suborder Symphyta. They undergo complete metamorphosis. The adult female uses a saw-like ovipositor to cut a slit in the fruit skin or flower base to deposit a single egg.
Physical Description
The destructive larvae are 1/2 to 3/4 inch long.
- **Larva (Key ID):** Small, smooth, cream-colored, caterpillar-like larva with a brown head. It has prolegs (fleshy legs) on the abdomen, distinguishing it from the legless grubs of weevils.
- **Adult Sawfly:** Small, dark, wasp-like insect that flies around the tree during bloom.
- **Damage Sign (Key ID):**
- **Ribbon Scar:** A distinctive, winding, ribbon-like scar that forms on the fruit surface as the fruit grows over the larva’s initial feeding tunnel.
- **Entry Hole:** A small, clean entry hole near the calyx (base) of the fruit, sometimes with dark frass.
- **Premature Drop:** High fruit drop shortly after the bloom period.
- **Conflict:** Fruit destruction, internal contamination, and cosmetic loss.
Distribution and Habitat
Quince Sawflies are found in fruit-growing regions of Europe and North America. Their habitat is the soil beneath the host tree (where they overwinter) and the blossoms/fruit in the spring.
Behavior and Conflict
The conflict is highly dependent on timing.
- **Critical Timing:** Control is highly time-sensitive, as the adult wasps are active only for a few days around the blossom period, and the larvae quickly enter the fruit where they are protected.
- **High Damage Threshold:** Even small populations can cause significant loss due to the severity of the damage inflicted on the fruit.
Management and Prevention
Control is integrated pest management (IPM), relying on bloom-time monitoring and timely chemical application.
- **White Sticky Traps:** Use white sticky traps placed in the tree during the bloom period to capture and monitor adult sawfly flight, determining the peak period for egg-laying.
- Apply a registered insecticide at the **petals-falling stage** (not during full bloom to protect pollinators) to kill the newly hatched larvae before they bore into the fruit.
- Minimize soil disturbance under the trees during the late summer/fall, as the larvae exit the fruit and drop to the soil to pupate and overwinter.
Conservation and Research
Quince Sawflies are managed as high-priority pome fruit pests. Research focuses on refining the temperature-based models (Degree Day models) used to predict the exact timing of adult emergence and the use of insect growth regulators.