About Flies

Flies reproduce rapidly under the right conditions. Most species begin as eggs laid on or near a food source. Eggs hatch into larvae (maggots), which feed on organic matter before developing into pupae and emerging as adults.

General lifecycle traits include:

• Rapid development, sometimes reaching adulthood in as little as a week
• High reproduction rates, often with hundreds of eggs per female
• Dependence on moisture for larval development
• Attraction to decaying material, garbage, drains, compost, and organic debris

Temperature plays an important role in fly development, with higher temperatures accelerating the lifecycle.

Lifecycle Dynamics in California

• Warm conditions throughout much of the year allow multiple fly generations in short periods.
• Coastal humidity supports stable populations of drain flies and fruit flies.
• Agricultural regions and areas with livestock may experience larger house fly and stable fly populations.
• Dry inland summers may reduce larval survival outdoors but increase fly activity near irrigated landscapes or homes.

These conditions contribute to prolonged fly seasons across the state.

Fly feeding behavior varies by species but generally includes the consumption of:

• Organic waste
• Rotting food
• Sugary liquids
• Fermenting material
• Animal waste
• Moist debris or decaying matter

Flies locate food through scent cues and frequently move between contaminated areas and indoor surfaces. Because they land and feed on multiple materials in rapid succession, flies can spread bacteria effectively.

Most flies are active during the day and rest on walls, ceilings, vegetation, or debris when not feeding.

Feeding and Activity in California

• Fruit flies are common indoors where fruit, produce, or compost is present.
• House flies increase near outdoor gatherings during warm months, especially in densely populated counties.
• Coastal regions experience consistent drain fly activity due to high humidity in older buildings.
• Agricultural zones throughout the Central Valley can experience house fly spikes after irrigation or harvest cycles.

Flies are adaptable and can live in nearly any environment that provides food and moisture. Common locations include:

• Kitchens, pantries, and garbage storage
• Drains, sinks, and floor traps
• Compost bins and recycling areas
• Outdoor waste containers
• Manure piles and livestock facilities
• Food preparation or food storage areas
• Windows, entryways, and light sources

Flies frequently travel through both clean and contaminated environments.

Common Fly Locations in California

• Urban areas with outdoor dining, farmers markets, or high waste volume
• Coastal cities where moisture encourages breeding sites
• Suburban homes with irrigated landscaping or backyard compost
• Agricultural regions with livestock, crop residue, or fermenting materials
• Older buildings where drains or plumbing systems accumulate organic debris

California’s long warm seasons and diverse environments support multiple fly species throughout the year.

Flies are considered significant nuisance pests with the ability to contaminate food and surfaces. Their feeding habits allow them to transfer bacteria and other organisms from one location to another. Potential concerns include:

• Contamination of food and food preparation areas
• Spread of bacteria acquired from waste or decaying materials
• Rapid population growth under favorable conditions
• Presence around indoor drains, garbage areas, or kitchens
• Annoyance during outdoor activities or in commercial settings

Flies do not bite in most cases, although certain species, such as stable flies, are capable of biting animals or humans.

Fly-Related Concerns in California

• Warm temperatures allow many species to remain active throughout much of the year.
• Fruit fly and drain fly issues are more prominent in coastal and urban regions.
• Agricultural operations in the Central Valley and other areas contribute to house fly activity.
• Outdoor dining and waste accumulation in metropolitan areas provide habitat for several fly species.
• Light, heat, and seasonal irrigation patterns influence indoor and outdoor fly movement.

These factors contribute to persistent fly presence across the state.