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Why do flies not leave you alone?

Flies can be extremely annoying, especially when they persistently buzz around your head and seem to follow you wherever you go. You may have wondered why flies are so attracted to humans and what makes some people more appealing to flies than others.

Why are flies attracted to humans?

There are a few main reasons why flies are attracted to humans:

  • Smell – Flies have an excellent sense of smell and are attracted to the natural odors and pheromones that humans give off. Sweat, breath, perfumes, soaps, and shampoos all contain chemicals that flies find inviting.
  • Carbon dioxide – Humans and other mammals exhale carbon dioxide when they breathe. The CO2 gas acts as a cue to flies that a potential food source is nearby.
  • Movement – A fly’s vision is attuned to detecting motion. As humans walk around and gesture with their hands, flies sense the movement and zoom in to investigate.
  • Heat – Flies gather around warm bodies, like humans and other mammals, to soak up heat energy.
  • Standing water – Flies need moisture to breed and develop. They are drawn to eyes, mouths, nostrils, wounds, and other wet bodily areas.
  • Food – Flies feed on sugars, proteins and fats. Saliva, sweat, tears, and other secretions contain nutrients that appeal to flies.

In essence, flies see humans as large food packages with appealing scents, carbon dioxide, warmth, moisture, and nutrition. By zeroing in on people, flies gain access to valuable resources they need to thrive and reproduce.

Why do some people attract more flies?

While flies bother everyone from time to time, some individuals seem to be more prone to attracting flies based on different factors:


  • Strong perfume/cologne
  • Scented hair products
  • Soaps with bold fragrances
  • Hand lotions or creams
  • Deodorant and antiperspirant

Flies use smell to locate hosts. Wearing highly fragrant personal care products makes you more noticeable to flies.

Carbon dioxide output

  • Larger people
  • Pregnant women
  • People who exercise vigorously

People who exhale more carbon dioxide due to their size or activity level can draw in more flies.

Standing water

  • Eyes (tears)
  • Mouth (spittle, drool)
  • Open wounds or sores
  • Moist or runny nose

Flies need moisture to lay eggs and nurture larvae. Wet eyes, mouth, wounds, and noses are breeding hot spots.

Poor hygiene

  • Body odor
  • Unwashed hair and skin
  • Soiled clothing
  • Crusted food spilled on clothes
  • Pet odor from animals

Lack of cleanliness increases body odors that appeal to flies, as well as food residue that flies want to access.

When are flies most active?

Flies tend to be most bothersome at certain times of day and year when conditions are optimal for them:

Warm weather

Flies thrive in warm temperatures and are most abundant in summer and fall in temperate climates. Cold winters reduce fly populations.

Daylight hours

Flies need light to see and avoid predators. They are most active on sunny, bright days.

Peak feeding times

  • Early morning – seek food after nighttime fast
  • Afternoon – build energy reserves before night

Flies aggressively seek meals early and late in the day to refuel.

Trash day

Flies congregate around garbage cans and dumps where food waste accumulates.

What attracts flies to certain body parts?

Flies zero in on specific body parts and regions when approaching humans. Here is what draws them to different areas:


  • Tears provide moisture for breeding
  • Eyelashes offer a perch to land on


  • Nostril moisture from mucus
  • Salty discharge attracts flies


  • Saliva contains sugars and proteins
  • Food particles cling to lips and teeth
  • Provides a warm, moist cavity for flies


  • Oozing blood and fluids for breeding
  • Damaged flesh raises odor profile


  • Perspire more than other body parts
  • Give off odors that flies can detect
  • Low to the ground where flies traverse

Flies have an uncanny ability to find and take advantage of human features and flaws that meet their needs for food, moisture, warmth, and breeding habitat.

What is the flies’ feeding and breeding pattern on humans?

Flies exhibit a distinct pattern of behavior when it comes to feeding, landed, and breeding on humans:


  • Circle overhead to locate potential food sources
  • Land and immediately look to eat
  • Regurgitate saliva to liquefy food
  • Use sponging mouthparts to soak up liquefied food
  • Look for moist surfaces, wounds, eyes, nose, mouth
  • Feed multiple times during the day


  • Prefer to perch on ankles, knees, elbows, hands
  • Groom themselves frequently when landed
  • Rub front legs over head to clean
  • Use hind legs to clean wings and abdomen
  • Briefly land to rest from flying


  • Seek moist surfaces to lay eggs
  • Preference wounds, eyes, mouth, garbage
  • Lay eggs in batches of 75-150 eggs
  • Larvae (maggots) hatch in 8-20 hours
  • Mature into flies in 2-4 weeks

This pattern maximizes a fly’s ability to gain nutrition, hydration, and breeding sites off the human body.

How many times a day do flies eat?

House flies and blow flies feed frequently throughout the day. Some key facts about their feeding habits include:

  • Feed 5-6 times per day
  • More active feeders in warmer weather
  • Must feed daily to survive as adults
  • Process liquefied meals quickly in 30-60 minutes
  • Regurgitate enzyme-rich saliva to begin digesting food externally
  • Liquified food absorbed through sponge-like mouthparts
  • Look for easy carbohydrate and protein meals
  • Preferred foods include fruit, garbage, carrion

The high metabolism and quick digestion of flies means they need to eat frequently throughout the day to acquire the nutrients and calories required for survival and reproduction.

What sense do flies use to locate humans and food sources?

Flies rely heavily on their senses of smell and vision to find desirable food sources like humans and locate places to land and feed:


  • Detect minute airborne molecules and odors
  • Attracted to carbon dioxide, perfumes, sweat
  • Can smell through their feet in addition to antennas
  • Detect smells up to 2 miles away


  • Excellent at detecting movement and shapes
  • See best in bright light, avoid shadows
  • Each eye composed of 4,000 lenses providing wide field of view
  • Able to see color, especially yellows and blues

Advanced olfactory and visual abilities allow flies to hone in on humans quickly by following attractive smells and movement patterns.

Do flies actually bite humans? What is their feeding mechanism?

Flies do not actually bite and pierce human skin like mosquitoes. They have a sponge-like feeding method:

  • Use sponging mouthparts called labella to sop up liquid
  • Regurgitate saliva onto food to dissolve solids
  • Lap up the liquified material
  • Saliva contains enzymes to start digesting food externally
  • Mouthparts designed to soak up dissolved matter
  • May scrape skin slightly with sponging parts
  • Capable of transferring bacteria from contaminated food sources

While flies do not bite, their sponging mouthparts come into contact with skin, making it possible for them to spread bacteria and disease.

What diseases can flies transmit to humans and food?

Flies are capable of picking up and spreading many dangerous diseases by transferring bacteria and pathogens:

Diseases from contact

  • Dysentery
  • Cholera
  • Salmonella
  • E. coli
  • Campylobacter
  • Ophthalmia

Diseases from ingestion

  • Typhoid fever
  • Diarrhea
  • Food poisoning

Parasitic diseases

  • Amebiasis
  • Giardiasis
  • Cryptosporidiosis

Flies transmit disease to humans directly when their body or mouthparts come into physical contact with people, food, or surfaces.

What are some effective ways to control and get rid of flies?

There are several strategies you can use to control flies and minimize their negative impacts:


  • Clean food waste promptly
  • Empty garbage frequently
  • Clean trash cans and bins
  • Clean dishes and surfaces
  • Clean up pet waste

Eliminating breeding sites limits fly population growth.


  • Install tight screens on windows and doors
  • Use screened lids on trash cans
  • Keep screens in good repair

Screens physically block flies from entering structures where food is stored and prepared.


  • Use attractant traps and sticky tape
  • Hang fly paper strips around your property
  • Set out container traps with bait

Traps lure flies in and capture them so they cannot bother you.


  • Apply insect repellent lotions and sprays
  • Use essential oils like lavender, lemongrass, citronella
  • Hang herbs like basil, mint, rosemary
  • Plant marigolds

Repellent odors deter flies from lingering on you or in an area.


  • Use ceiling fans indoors to disrupt flies
  • Place oscillating outdoor fans in gathering spots

Fans make it difficult for flies to land and bother you.


Flies can be a nuisance, but there are reasons why they are so attracted to humans. Their exceptional senses allow them to target people as food sources and habitat for breeding. Sanitation, traps, repellents, and fans can be applied to reduce fly populations. Understanding fly behavior patterns and preferences helps explain why these pests won’t leave you alone and how to discourage them more effectively.