**Olive Fruit Flies** (*Bactrocera oleae*) are highly specialized tephritid fruit flies and are the most important and destructive insect pest of olive (*Olea europaea*) crops worldwide. The conflict is total commodity loss: the female fly lays eggs inside the developing olive fruit, and the larva (maggot) tunnels through the pulp, causing premature fruit drop, reducing oil quality (increased acidity), and rendering table olives completely unusable due to maggot presence, leading to **massive economic loss**.
Taxonomy and Classification
Olive Fruit Flies belong to the order Diptera (Flies). They undergo complete metamorphosis. The fly is an obligate pest of olives and its closest wild relatives. It has multiple overlapping generations per year, creating continuous pressure on the fruit from mid-summer through harvest.
Physical Description
Adult flies are small, 4-5 mm long.
- **Adult Fly (Key ID):** Shiny, dark brown fly with clear wings that have a distinct, small, black spot near the tip.
- **Larva (Maggot – Key ID):** Creamy white, legless, tapered maggot found inside the olive fruit pulp.
- **Damage Sign (Key ID):**
- **Puncture Mark:** A tiny, dark, triangular oviposition (egg-laying) puncture mark on the olive skin, sometimes surrounded by a halo of discoloration.
- **Internal Damage:** A large, winding tunnel carved through the pulp, often visible when slicing the olive.
- **Pre-harvest Drop:** Increased premature fruit drop.
- **Conflict:** Severe agricultural commodity destruction (olives).
Distribution and Habitat
Olive Fruit Flies are native to the Mediterranean region and have been introduced to many olive-growing regions, including California. Their habitat is restricted to olive trees, particularly the developing fruit.
Behavior and Conflict
The conflict is total loss of harvest potential.
- **Quality Degradation:** Larval feeding increases the acidity of the oil, reducing its grade and market value. For table olives, the presence of even minor damage renders the fruit unusable.
- **High Reproduction Rate:** The ability to produce multiple generations in quick succession, coupled with the single host plant, means control must be constant throughout the growing season.
- **Hidden Pest:** Much of the damage is internal and hidden until the olive is processed or cut open.
Management and Prevention
Control is integrated pest management (IPM), dominated by monitoring and lure/kill strategies.
- Use sticky traps (yellow or white) baited with specific pheromones and protein hydrolysate lures to monitor fly populations and time control interventions precisely.
- **Lure-and-Kill:** Apply a localized, spot-treatment of a protein bait mixed with a small amount of insecticide. The flies are attracted to the protein and ingest the toxicant before laying eggs. This minimizes broad-spectrum insecticide use.
- **Mass Trapping:** Use large numbers of traps (containing bait and toxicant) across the orchard to capture and kill females before they lay eggs.
- Sanitation: Promptly remove and destroy all fallen, infested fruit during the season.
Conservation and Research
Olive Fruit Flies are managed as high-priority pests in commercial olive production. Research focuses on developing sterile insect technique (SIT) programs, understanding resistance to lures, and improving biological control through natural enemies.