Fleas will pose a hazard (health) to both pets and humans. So, ensure to flea-treat your cats & dogs –  to avoid that massive infestation. 

But what attracts fleas? As they find a host, cat fleas are mainly attracted by thermal and visual stimuli (heat & light). Others include C02 & exhaled breath from humans, movement, darkness, food, and warmth. 

Attraction Cues:

• Host size & color, time of day, carbon dioxide, physical contact, warmth, gravity, host odor, air currents, and light movement. 

Related: Do Fleas Suck Blood

Details: What Attracts Fleas?

When it emerges from its cocoon, adult fleas will begin sucking blood for survival – avoiding starvation will require feeding within a week. 

Cat fleas will largely be attracted by thermal and visual cues. But combining various stimuli will enhance the accuracy of how the fleas detect their hosts.

1. Phototaxis (Light)

Light will attract those adult fleas – this will mainly be the green-yellow light with wavelengths of 500 to 530 nm.

• Turning the lights on or off quickly makes the fleas perceive such actions as a shadow from some possible host in the surrounding. 
• Thus, intermittent light will attract the fleas for about 8 times more compared to using continuous light.  

Notably, when positioned in dark places, over 90% of all fleas will start moving to areas with light within 1 hour. 

a. Intermittent Light 

The light attraction for fleas will be better when the source of light is briefly & quickly interrupted within like 5-10 minutes. 

• As noted above, the light interruption seems to mimic some shadow that would be produced by some potential host when its passes by the bug. 

Thus, fleas will tend to quickly jump towards the side that had observed shadow. 

Flea traps that employ intermittent lighting will be effective in attracting and capturing more fleas compared to the use of lighting that is constant. 

b. Color of Light 

Fleas, especially cat fleas, will be attracted to different color wavelengths – for example, most fleas will get attracted by light at wavelengths of 300 to 600 nanometers (nm). 

However, generally, fleas will get attracted by the light colors that have wavelengths of 500 to 530 nm, this is what we call green-yellow in color. 

• The light that has a green-yellow color will attract over 100% more fleas compared to the standard light. 

You can improve the performance of your various fleas traps by outfitting them using some green-yellow filter. 

However, some colors such as green and blue filters won’t be as effective in attracting fleas and will have a comparable effect to that of standard light. 

• Finally, other color filters (compared to standard light) will give better outcomes in attracting fleas; such colors include medium blue, yellow, magenta, and red. 

It’s vital to note that fleas won’t easily see lights with wavelengths that are over 630 nm including red light.

2. Host Odor (Odortaxis)

Different flea hosts have an odor that’ll attract fleas – this is because the primary host provided them with shelter plus food (that critical blood meal). 

• Thus, some flea species will be attracted by some host odors and not others.

But it’s not clear whether cat fleas will be practically be attracted to cat body odor. 

3. Movement moving objects attract fleas

Fleas won’t be attached to stationary and inanimate items.

For instance, a recent study reported that over 75% of fleas were attracted by a black (moving) target.

• However, in the same experiment, just under 20% of the fleas got attracted to the object in its stationary form.

Further, another study reported that stationary (and warm) objects make the fleas jump with the presence of other stimuli like air currents. 

• Fleas will produce about 20 eggs in the pet’s hair – these eggs tend to fall off onto some furniture, floors, and carpets. 
• While in such locations, the fleas and their larvae hide in the dark locations and shadows as they eat flea dirt (undigested blood). 

The shadows and fabric or carpet fibers will hide the fleas as they develop into pupae & as they spin those silky cocoons. 

4. Air Currents/ Air movement (Anemotaxis)

Air Currents won’t attract fleas on their own – this is to say that your fan causing air movements of fast air currents won’t attract those cat fleas.

• But when coupled with various factors, air movements or currents will attract fleas.

But air currents coming in short bursts will cause flea jumping, although there is no relationship with fleas’ attraction.

5. Gravity (Geotaxis)

Considering gravity, fleas will be negatively gravitactic (geotactic), and thus it’ll be moving anti-gravity. 

• The baby fleas will climb onto small items – they’ll remain on top and also wait for any animal that’s passing by. 

In your apartments, check the carpet fibers as this will be where you’ll find the adult fleas. 

• When in the outdoor spaces, fleas will climb onto some shrubs or vegetation. 

6. Are fleas attracted to CO2?

Carbon dioxide will also attract bugs like bed bugs and fleas – CO2 is that gas that warm-blooded animals breathe out. 

• Thus, fleas could actually prefer hiking on some individuals as opposed to others in your house. 
• This is because some people will give off mo0re CO2 in comparison to others – and thus such individuals will be flea-infested more. 

Fleas, especially cat fleas, will leap around more when there is a higher CO2 amount. 

• Besides, CO2 produced by humans tends to attract fleas more – this might down that humidity and warmth could increase the level of fleas’ response. 

Further, a recent flea study shows that the bugs’ activity & jumping as they’re receiving CO2 in short bursts.

7. Warmth (Thermotaxis)

The activity of fleas in your spaces will reduce when there is an increase om heat – a positive response on the thermotactic conditions. 

• Notably, the fleas will jump all over via casual directions especially when you place some warm item in the bugs’ environment.

Fleas will get attracted by warm temperatures since it mimics the presence of a possible host – due to their body warmth. 

• The temperature target will be around 40°C (104°F) – including objects and animals. 

But you’ll also experience some flea attraction around a temperature of 50°C (122°F) – and thus it’s clear that fleas might not easily discriminate against various hosts. 

• Despite that fleas may orient towards some heated item, the bugs will require additional stimuli including factors like air or current movement. 

8. Host Size & Surface Color

Fleas won’t get attracted to hosts with small bodies. Hosts like rodents and moles won’t largely attract fleas. 

• A recent study employed such a target to determine the suitability of small hosts to fleas.
• Thye used targets that have diameters as follows 20, 13, & 8 centimeters – the fleas’ responsiveness to the targets was noted as 44%, 43%, & 21% respectively. 

On surface colors, fleas’ attraction was analyzed considering colors including white, yellow, black, blue, and red. The outcome was that blue and red are highly attractive and white is the least. 

Conclusion

In summary, on the question “what attracts fleas”, fleas will be attracted to thermal and visual stimuli – like warmer places and hosts – I would say temperatures around 65 degrees. 

• Fleas seek warmth from locations such as the pet’s nestling and fur, or even their skin. 

Other stimuli that’ll attract fleas are C02 & exhaled breath from humans, movement, darkness, food, and warmth. Further factors include air currents, light movement, and host size & color.