Fruit flies, scientifically known as Drosophila melanogaster, are small insects commonly found in homes, often drawn to ripening fruits and vegetables. Understanding how cold temperatures influence their presence and survival is a frequent question.
Preferred Environments
Fruit flies thrive in warm and humid conditions, which are ideal for their life cycle and reproduction. Their optimal temperature range for development and activity is generally around 25°C (77°F). At this temperature, their generation time is notably short, taking approximately 9 to 10 days from egg to adult. Temperatures between 20°C (68°F) and 25°C (77°F) are considered favorable for their life cycle and reproduction.
Female fruit flies are less likely to lay eggs in cooler temperatures, which inhibits their breeding. While they can still be active in winter, their development is significantly delayed in cooler conditions.
How Cold Affects Fruit Flies
Fruit flies, as ectotherms, have body temperatures that align with their surrounding environment, meaning they cannot regulate their internal temperature. When temperatures drop below their preferred range, their physiological processes are significantly impacted. Below approximately 18°C (65°F), their lifespan shortens, and their metabolic rate decreases.
Exposure to low temperatures can lead to a state known as “chill coma,” where the flies lose their ability to move and respond, effectively becoming immobilized. For Drosophila melanogaster, the chill-coma temperature can range from -0.1°C to 4.5°C, depending on factors like developmental temperature and geographical origin. During chill coma, their gut can become leaky, leading to an imbalance of salts and water that can cause cell death if severe enough. Unlike true diapause, Drosophila melanogaster typically experiences a reversible cold-induced quiescence.
Temperatures below 12°C (53.6°F) can severely inhibit or halt their development. Larvae may not develop into adults at temperatures around 10°C (50°F) or lower. Continuous exposure to temperatures below 7°C (45°F) can be lethal for adult fruit flies.
Cold as a Control Method
Utilizing cold temperatures can be an effective way to manage fruit fly populations within a home. Since these pests are drawn to ripening and overripe produce, refrigerating fruits and vegetables is a practical strategy. The cold environment of a refrigerator, typically around 4°C (40°F), slows down the ripening process and inhibits fruit fly development and breeding.
For items heavily infested or food scraps destined for compost, placing them in a freezer can eliminate fruit flies and their eggs. While cold temperatures may not instantly kill adult flies, they significantly reduce their activity, lifespan, and ability to reproduce, preventing further infestations.