Are Fleas Attracted to Heat?

As fleas search for food or flea dirt, they’ll be attracted by different stimuli to know a fitting host – are thermal and visual the main stimuli for attracting fleas? 

So, are fleas attracted to heat (Thermotaxis)? Yes, over 90% of fleas will be attracted to fleas within 30 minutes but on its own, it has limited effectiveness in host-finding. 

Combining various stimuli such as movement, heat, and light (or shadows) will result in a higher attracting response on the fleas. 

Details: Are Fleas Attracted to Heat? Thermotaxis?

As noted above, cat fleas will get attracted to their hosts through stimuli and thermal cues or stimuli. Thermotaxis denotes the aspect of repulsion or attraction towards heat.

  • So, cat fleas are considered to be attracted and stimulated by heat or warmth – which means that they’re positively thermotactic. 
  • The positive thermotactic response in fleas allows them to location possible hosts and blood meals – this is because fleas’ hosts will emit some body warmth or heat. 

But how do fleas detect heat? The fleas’ antennae-like organ will work like some sensory organ. So, the fleas’ antennae will recognize different cues including heat or warmth. 

  • Studies have reported that flea infestations significantly increase when there is a rise in warmth in the surrounding or heat. 

If warm objects are positioned in the fleas’ environment, the bugs will jump randomly. The warm informs the fleas that there could be a possible host such as cats & dogs. 

  • Naturally, fleas love areas that are warmer. This includes places that have around 65 degrees of temperatures – and thus pets will make excellent hosts with their warmth.

Besides getting a great blood meal supply on the pets like cats & dogs, fleas also enjoy the pet’s warmth. 

  • Fleas will use pets to gain entry into your house or apartment. But fleas may also hitch-hike your second-hand furniture or clothing. 

When the fleas emerge from the cocoons, they’ll start searching for a blood meal. If they don’t get some blood meal, the bugs will starve within 1 week. 

Recent studies report that when fleas are positioned in a dark area, over 90% of them will jump into the areas with light in just 30 minutes. 

  • Considering lights, standard light will have a lower ability to attract fleas to those green-yellow lights.
  • Besides, the fleas’ attraction to heat or light will increase if the light source is turned on plus then off and on in quick succession – this mimics the movements of a flea host.

Further, flea traps that utilize intermittent lighting tend to attract & trap more (about 82%) of these bugs. 

The bugs will jump towards the heat source – as they’ll get attracted to temperatures around 40°C (104°F). 

However, they’ll still get attracted by temperatures rising to highs of 50°C (122°F); and thus the fleas could hitchhike a number of hosts due to variation in temperatures that attract them. 

Heat Alone won’t Promote fleas’ Host-Finding Habits

Despite that heat or warmth will attract fleas, this cue (alone) won’t work to attract the bugs towards their suitable hosts. 

  • The bugs will orient their bodies to some warm gadget and aim to jump, but they’ll only jump if there are other stimuli in the environment. 

For example, flea-control gadgets like flea traps that use just heat as their sole stimulus will not attract the bugs. 

  • Further, for the flea trap using light, including some heat will not boost its fleas’ attracting performance and host-detecting. 

Fleas Abandon their Hosts with Low Temperatures

Fleas will remain on their chosen host after they’ve landed on such animals. However, fleas will leave that host once it’s dying or dead. 

  • The bugs learn this if the body temperature of the host animals starts to drop.
  • Thus, the bugs will hitchhike another host or animal that is warm.

Further, fleas may jump onto some predator’s body after such an animal has killed a flea-infested prey. 

Pre-emerged Flea Adults on Hosts

Pre-emerged adult fleas will respond positively to heat as an attraction cue.

  • After these younglings are adequately developed, they’ll stay in cocoons up to when they detect some host. 

The young fleas will be in the quiescent stage for about 5 months – they’ll mainly be triggered by physical pressure and heat such as from a fleas’ steam cleaner

  • The occurrence of pressure and heat will denote to the bugs that there is some nearby warm-blooded host. 

The fleas emerge from those cocoons also due to the human breath that is warm. Another gadget I recommend for triggering the fleas’ emergence is the flea vacuum. 

  • Will fleas be attracted to cold or heat? Well, fleas will flourish in humid and warm environments – which is about 75°F – with their activity slowing down in winter. 

Thus, during winter, the house and apartment will offer an appropriate habitat for fleas to grow especially if there are household pets like cats & dogs. 

For outdoor spaces, fleas will love humid, moist, & shady areas such as the yard or lawn.


So, on whether fleas are attracted to heat, YES fleas will be attracted by fleas but it must not be the only cue or stimuli.

Fleas prefer to respond positively to a combination of various stimuli including movement, heat, and light. 

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