School IPM Best Practices

Fruit Flies (Vinegar Flies), Drosophila spp.

Fruit fly

Mohammed El Damir, Pest Management, Bugwood.org.

IPM Steps to Reduce Fruit Flies

1. Sample for Pest

Confirm the presence of fruit flies.

Where to find it while inspecting: Adults can be seen flying around fruits and vegetables, especially ripe fruit, and liquids such as cider and vinegar. Eggs are often the source, as they are too small to be seen and often have been laid on a fruit or vegetable before you receive delivery. They are also found near drains and along the floor where decaying food scraps linger. Adults tend to hover in groups but are often seen resting on wall surfaces. NOTE: They can be found within food processing and dishwasher equipment.

2. Proper ID

Before you act, determine your pest is a fly and for best results, which species of fly.

Size and Appearance: 1/8" (3 mm) long, light colored with red eyes.

3. Learn the Pest Biology

Knowing the life cycle helps you fight fly infestations.

Life Cycle: Females lay about 500 eggs near the surface of fermenting fruit and vegetables or the edges of food containers. Eggs hatch in about 30 hours and fed for 5–6 days. Mature larvae crawl to drier areas to pupate. Pupa look like tiny brown seeds. Adults emerge and are ready to mate within two days. A full life cycle can be 8–10 days.

Preferred Food Sources: Fermenting foods, especially fruits and vegetables, as well as human and pet waste.

Preferred Habitat: Fruits and vegetables, food containers, floor drains, food processing and dishwasher equipment.

4. Determine Threshold

Flies are annoying, but what is your threshold for infestation? When should you act?

Threshold: Because of their short life cycle, once you’ve seen a few fruit flies you need to act.

5. Choose Tactics

IPM for indoor pests is always a combination of exclusion and sanitation: Try to keep them out. Don’t provide water, food and shelter if they enter your building.

Best Management Practices: Reduce organic build up near floor drains and in sinks and garbage cans. Check incoming food deliveries for signs of adults. Wash fruits and vegetables well upon receipt. Be especially vigilant in late summer, early fall when numbers are most high in the Northeast. If you suspect they are breeding outside, near your kitchen entrance, you may want to install a smaller weave screen over windows. Sanitation and inspection is the best preventive. Keeping fresh/raw fruits and vegetables in a cooler reduces infestation. Rinse them well to remove eggs.

Treatment Methods: Reduce organic build up near floor drains and in sinks and garbage cans. The presence of adult flies inside means they are developing nearby. Use baited traps to reduce adults and be patient as this is not effective on eggs, larvae and pupae. Good cleaning of surfaces and floors is key. Remove protective covers from food processing and dishwasher equipment to inspect and clean.

6. Evaluate

Was the tactic successful? Record the date pests were first noted, and the tactic you used, and its success. Use one of our RECORD KEEPING tools.

For More Information:

University of Florida School IPM: IPM for Flies in Schools


When a pesticide application is necessary, all necessary and required precautions are taken to minimize risk to people and the environment and to minimize risk of pesticide resistance or pest resurgence. Pesticide use in your school may be prohibited or regulated by local policies or state and federal regulations. Risk reduction methods can include, but are not limited to, spot-treatment, the use of gel or paste bait formulations placed in inaccessible locations, injection into a crack or crevice, and other methods that reduce potential exposure.