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Horse wearing a fly mask

Why Me? Understanding the Science Behind Insect Attraction

Written by: Lucy de la Pasture

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Published on

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Time to read 4 min

If you’ve ever returned from a relaxing hike or ride with more bites than your companions—or watched your horse being harassed by swarms while others graze in peace—you’re not imagining things. Some people and horses really are more attractive to biting insects. But why?


Understanding the reasons can help you manage insect pests more effectively and enjoy the outdoors with fewer itchy consequences.

The Top Culprits: Who’s Biting?

1. In the UK and many temperate regions, the most common biting insects are:


  • Mosquitoes – active at dusk and dawn, notorious disease vectors.

  • Midges – particularly Culicoides species, which swarm in clouds near water.

  • Horseflies – large, fast-flying insects with painful bites, active in sunlight.


Each species has evolved to detect their hosts using sight, smell, heat, and movement , and some of us (and our horses) just give off stronger signals.


Icaridin Insect Repellent - most effective against biting flies

1. Body Odour and Skin Chemistry


Human and animal skin emits hundreds of volatile organic compounds (VOCs). These odours, produced by sweat and bacteria on the skin, can make you either a magnet—or a repellant—for biting insects.


A 2022 study in Current Biology found that people who produce more carboxylic acids , a type of fatty compound, are consistently more attractive to mosquitoes. These acids are natural byproducts of skin cell turnover and vary genetically and microbiologically.


Similarly, horses have unique sweat chemistry. Some horses sweat more, and the breakdown of their sweat by bacteria can create odours that insects find irresistible.


Try this : Wash your horse down regularly or after exercise with peppermint or lavender shampoo. For yourself, avoid perfumed lotions that may enhance your scent signature.


Reference :

  • De Obaldia, M. E., et al. (2022). "Differential mosquito attraction to humans is associated with skin-derived carboxylic acid levels." Current Biology, 32(6), 1211–1222.e4. DOI: 10.1016/j.cub.2022.01.073 


All biting insects are attracted to carbon dioxide (CO₂) —the gas we exhale. Larger individuals (human or equine) naturally exhale more CO₂, making them easier for insects to locate. Activity increases this even further.


🏇 Horses, especially large breeds, emit considerable CO₂. Combined with their size and warmth, they’re ideal targets.


Reference :

  • Dekker, T., et al. (2005). "Carbon dioxide and 1-octen-3-ol as mosquito attractants." Journal of Medical Entomology, 42(5), 709–715.

3. Body Heat and Infrared Radiation


Insects like mosquitoes and horseflies use infrared sensors to find warm patches of skin. After exercise or on a hot day, humans and horses become veritable beacons to bugs.


Tip : Use breathable fly sheets, fly masks, or long, light-coloured clothing to reduce visibility to these pests.


Reference :

  • Braverman, Y., & Chizov-Ginzburg, A. (1998). "Attraction of horseflies to heat: the role of body temperature." Medical and Veterinary Entomology, 12(3), 322–325.


 

Different people (and horses) host different microbial communities , and these bacteria influence odour. Certain bacteria increase insect-attracting compounds.


Research in PLoS ONE shows that skin microbiota can significantly influence how likely you are to get bitten.


This may also explain why horses in different environments attract different levels of flies.


TIP: Apply icridin insect repellent


Reference :

  • Verhulst, N. O., et al. (2011). "Composition of human skin microbiota affects attractiveness to malaria mosquitoes." PLoS ONE, 6(12): e28991.

It's all in your genes! Genetics affect odour, immune response, sweat composition, and even how you react to bites. Some people swell up, others don’t. Mosquitoes prefer Type O blood over others, according to research in Scientific Reports.


While you can’t change your genes, knowing your risk helps in planning deterrents.


REFERENCE

  • Manica, M., et al. (2017). "Mosquito attraction varies according to human genetic variation and ABO blood group." Scientific Reports, 7, 15106.

Insects are visual creatures. Horseflies and mosquitoes prefer darker colours like black, navy, or red.


Studies from the University of Lund found that horseflies are drawn to dark, shiny surfaces due to their polarised light reflection.


Field tip : Dress in light-coloured, loose clothing. Light-coated horses or those in light fly gear or Zebra-striped rugs often receive fewer bites.


Reference :

  • Egri, Á., et al. (2012). "Polarotactic tabanid flies are attracted to darker targets: why horses with a dark coat suffer more?" PLOS ONE, 7(10), e44602.



Moving targets are more easily spotted and pursued by insects. Riders, hikers, or restless horses are easier for insects to lock onto.


Some horse owners notice their more active horses get bitten more—this isn’t bad luck, it’s biomechanics.


Reference :

  • Vale, G. A. (1974). "Responses of tsetse flies (Diptera: Glossinidae) to mobile and stationary baits." Bulletin of Entomological Research, 64(2), 199–208.


For Humans

  • Use icaridin-based repellents

  • Wear long sleeves and light colours

  • Be aware of the times when you're most likely to be bitten

  • Consider taking vitamin B12

  • Keep moving air around with a fan




For Horses

  • Use fly sprays and insect-repelling shampoos

  • Consider garlic supplements (consult your vet)

  • Fit lightweight fly rugs and masks

  • Provide shelter and shade

  • Use integrated non-chemical controls such as horsefly traps

  • In hot periods, use fans in stables to deter flying insects.

Yes, some people and horses truly are more attractive to biting insects. The reasons include skin chemistry, microbiota, genetics, and even your shirt colour.


By understanding the science, you can take action to keep yourself and your animals more comfortable—and bite-free—while enjoying the outdoors.

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