Flies are common household pests that can be annoying and spread disease. Understanding flies’ preferences for light or dark rooms can help homeowners use light strategically to repel flies or attract them to traps. This article will examine research on flies’ vision and light preferences to determine if flies like light or dark rooms more.
Flies’ Vision
Flies have compound eyes with thousands of individual light receptors. This gives them nearly 360-degree vision and allows them to see ultraviolet light that humans cannot. Flies’ compound eyes are optimized for detecting movement and light contrast rather than visual details or colors.
Do Flies Prefer Light or Dark Areas?
Research indicates that flies generally prefer dark over very bright light. Their compound eyes are sensitive to light, and extremely bright light can overwhelm and deter flies. However, flies are also drawn to some light, particularly ultraviolet light. Let’s examine fly behavior in light versus dark spaces in more detail.
Dark Spaces
Flies tend to gather and rest in dark, sheltered areas. These shaded areas protect flies from predators, intense light, and wind or weather. Some examples of dark spaces flies prefer include:
– Inside closets and cabinets
– Beneath furniture
– Behind curtains
– Underneath sinks and counters
– Inside unlit garages or basements
The darkness provides cover and safety for flies to rest undisturbed.
Dimly Lit Spaces
While flies avoid intensely bright light, they are attracted to some forms of light. Flies gather around dim light sources, drawn in by the ultraviolet wavelengths. Some examples of dim light that attracts flies includes:
– Sunlight coming in windows
– Gaps around doors and windows
– Nightlights or dimmed lamps
– Light from TVs or appliances
– Dusk and dawn light
These dim light sources appeal to flies as areas to gather, feed, and mate. The light aids their vision without deterring or harming them.
Experiments on Fly Light Preferences
Scientific lab experiments help quantify flies’ light preferences. Here are the results of some key studies:
Aversion to Bright Light
In lab tests, house flies avoided lit areas of an enclosure and preferred dark shelter areas. With a 60-watt bulb, the flies chose the dark area 90% of the time. Even with a 25-watt bulb, they still chose the dark side 65% of the time. This demonstrates an aversion to bright light.
Attraction to UV Light
Multiple studies show flies are attracted to ultraviolet light wavelengths between 350-380 nm. Flies gather around UV emitting light traps. Using filters to block UV light reduced flies’ attraction to the light by up to 92% in one experiment. This indicates flies have a strong orientation toward UV.
Positive Phototaxis at Low Light Levels
Phototaxis refers to an organism moving toward or away from light. In low light conditions, flies exhibit positive phototaxis and move toward the light source. For example, in dim rooms with light emitting diodes (LEDs), flies oriented themselves toward and moved closer to the LEDs. So flies are attracted to faint light.
Why Are Flies Attracted to Some Light?
While flies avoid intensely bright light, they gather around dimmer light sources for the following reasons:
– **Ultraviolet wavelengths** – Flies see UV light that leads them to light fixtures.
– **Vision enhancement** – Low lighting allows flies to see better than total darkness.
– **Warmth** – Flies are cold blooded and gather near lights that emit warmth.
– **Food odors** – Light aids flies’ ability to smell and locate food sources.
– **Mating** – Light helps flies see and pursue mates effectively.
So dim light helps flies maneuver, find food and mates, and stay warm, making it preferential over complete darkness.
Do Flies Sleep at Night?
Yes, flies are generally inactive at night when it is dark. Light is their visual cue for daytime activity and darkness signals nighttime rest. However, flies may still be active around artificial lights at night. Their nighttime routine includes:
– **Resting** – Flies pick sheltered, dark spots like corners of rooms to settle down at night.
– **Reduced Activity** – Flies are mostly stationary at night and conserve energy. Their metabolism lowers by about 10-20% at night.
– **Short Naps** – Flies take many short snoozes rather than one long sleep. Naps may last around 15 minutes.
– **Comfort** – Cooler nighttime temperatures help flies sleep. They prefer temperatures around 20°C (68°F).
So flies do indeed sleep at night when natural light dims, but artificial lighting can disrupt their circadian rhythms.
Do Flies Sleep During the Day?
Flies are mostly active during daylight hours when they forage, mate, and look for food and breeding sites. However, flies do take short naps during the day of about 15 minutes. When resting during daylight, flies:
– Seek out dark, hidden nooks and crannies away from activity.
– Partially close their eyes by drawing down their upper eyelid to block out light.
– Enter a temporary state of inactivity to conserve energy.
– Reduce their metabolic rate by around 10% while napping.
– Remain alert enough to still detect predators while napping.
So flies nap sporadically both day and night, but their longer sleep sessions occur when it is dark at night. Daytime light keeps them more active.
Tips for Deterring Flies by Manipulating Light
Here are some tips to make rooms less welcoming to flies by strategically using light:
– Install bright overhead lights, especially UV emitting lights, which discourage flies.
– Keep blinds or curtains closed on windows in bright sunlight, as flies are attracted to UV rays.
– Seal any gaps letting light into dark rooms where flies may be resting.
– Use dim nightlights instead of bright lights at night to avoid attracting flies.
– Vacuum and clean any infested areas at night when flies are sluggish.
– Illuminate entryways with overhead lights and use fly zappers to deter flies.
Tips for Trapping Flies with Light
To draw flies out and trap them, take advantage of these positive phototaxis techniques:
– Place UV LED fly traps in dark corners or fly activity hot spots. The UV will pull flies in.
– Hang fly paper strips near entryways at night drawn in by overhead lights. The paper will catch flies.
– Put out bowls with sweet liquid to attract flies in lighted doorways or windows. The liquid will drown flies.
– Install window fly traps that suction flies to the lighted exterior of windows.
– Use light timers during evenings or mornings when flies are active to automatically turn on lights and trap flies.
So strategic use of light or dark conditions can either repel flies or lure flies to their demise.
Conclusion
To conclude, flies generally prefer darkness over bright light which overwhelms their vision. However, flies are attracted to some forms of light, particularly ultraviolet light, that aids their ability to see, navigate, find food, and mate. Flies rest in darkness at night when inactive but take short naps in dark corners during daytime as well. Homeowners can manipulate light strategically to either deter flies by using bright overhead lights or trap flies by luring them into illuminated fly traps and glue boards. Considering flies’ light preferences and vision capabilities allows for effective fly management.
