Pest profile

Olive Fruit Fly

Bactrocera oleae · Diptera: Tephritidae[2]

The olive fruit fly now occurs in all olive-growing areas of California, and its maggots rot the fruit of both commercial and ornamental trees.[1]

Olive fruit fly adult with brown body, pale patches on the thorax and clear wings with dark tips, on a leaf
Olive fruit fly adult with brown body, pale patches on the thorax and clear wings with dark tips, on a leaf. (c) Katja Schulz, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are about 1/4 inch long, brown with darker marks and white or yellow patches on the thorax.[1]
  • Wings are held horizontally away from the body and have black spots at the tips but no bands.[1]
  • Maggots are yellowish white and legless with pointed heads, inside the fruit.[1]

Look-alikes

Look-alikeHow to tell them apart
Walnut husk fly and apple maggotThese related fruit flies have banded wings; the olive fruit fly has only dark wing tips.[1]

Where it lives

First found in California in west Los Angeles in 1998, it now occurs in all of the state's olive-growing areas.[1]

US map: public records from 2 states since 1990 (GBIF).

Biology and life cycle

On the mild coast, adults are active year round; inland they emerge March to May and attack leftover olives.[1]

Females lay eggs in the new crop from about late June or July, usually one per fruit.[1]

Damage and signs

  • Maggots destroy the pulp and let in bacteria and fungi that rot fruit and spoil oil.[1]
  • Infested fruit drops early, and rotting fruit on the ground creates a mess in landscapes.[1]

Health risk

It feeds on olives; UC IPM mentions no risk to people.[1]

Control

Prevention

Harvest early and press infested fruit quickly to limit off flavors.[1]

Sanitation

Pick up fallen fruit, harvest promptly, and knock remaining fruit off trees after harvest; mulch, mow or bury it at least 4 inches deep.[1]

Pesticides

A spinosad bait spray, started when traps catch flies or 2 to 3 weeks before pit hardening, kills adults that feed on it; follow the label.[1]

Common questions

Why are my olives rotting and dropping?
Olive fruit fly maggots feeding inside let rot organisms in and cause early drop.[1]
How do I tell it from other fruit flies?
Look for dark wing tips and no wing bands.[1]

Sources

  1. University of California Statewide IPM Program, “Pest Notes: Olive Fruit Fly (Publication 74112).” ipm.ucanr.edu/PMG/PESTNOTES/pn74112.html (accessed 2026-10-06)
  2. iNaturalist, “Bactrocera oleae taxon page (order and family).” www.inaturalist.org/taxa/326609 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.