The flea is a fascinating creature! However irritating it may be to us and our pets, we can’t deny that the adaptations it has developed for survival are pretty impressive.
For example, the powerful spring action of the flea’s hind limbs that can allow it to jump 100 times its height in order to gain access to the target host. The mechanism of how the flea could jump so high mystified scientists for decades, with a 1967 study unlocking part of the answer, but it took until 2011 to find another piece to the puzzle. In simplified terms, the hind limbs bend to store potential energy like a spring, while the feet anchor the flea while the energy is stored. When the flea jumps, all of the stored energy propels the flea high enough to jump onto its warm-blooded host (which translates to the height of a cat or dog, or lower-leg height in people!) They then use their special saliva to soften the skin in order to let the flea feed on their host’s blood (unfortunately for us, a side effect of the flea saliva is to cause irritation and itching, and for some animals an allergic reaction of the skin).
Another advantage the flea has to help it survive is the almost indestructible pupal stage of its life cycle. After the smooth, oval flea egg is laid, it rolls off the animal’s fur and lands on the floor. The egg then hatches into a larvae, which eats the adult flea excrement (dried blood) and other organic material in the environment (dead skin cells etc). After a few days, the larvae spins a cocoon and becomes a pupa. This is the stage at which it is extremely difficult to kill the flea. The pupa can exist in this state for up to a year, and will not hatch unless the conditions are right – in other words that there are signs of hosts nearby. Clues that indicate a dog or cat may be in the vicinity are heat, vibration and carbon dioxide levels (from the animal’s breathing). If none of these are present the pupa will just bide its time. This is why you can move into a house that has been empty for months, and start getting bitten by all those little newly emerged fleas!
The life cycle of the flea is also the reason that it can be so difficult to get on top of a flea problem. Unfortunately, once you see evidence of fleas on our pets and in their habitat, it is often very difficult to become flea-free again quickly. Once you notice fleas, it is a guarantee that they have already been around long enough to have produced hundreds of eggs. All of the pupae that have formed from these are within the environment, hiding out in cracks and crevices. Treatment starts with the animal, usually with a spot on flea treatment, perhaps combined with a fast acting oral treatment to get instant results. Any adult flea that is on the animal will be killed, but what about all of those pupa waiting to hatch into new adult fleas? Even if you use an environmental treatment as well, which is ideal, the pupae will not be vulnerable to it. They will continue to hatch, and jump onto your pets. They will be killed by the treatment you have applied to the animal, but not until after they’ve had a bit of lunch! Many people believe that the flea treatment that they are using is not effective, because they do not realise that the live fleas that they see on their pets post-treatment are new ones emerging from the pupae in the environment. In other words, it may take a few months of monthly treatments before you will be on top of the problem, as all of the pupae in the environment have to hatch first and all of those new adult fleas killed.
So the best way to avoid the warm weather flea explosion? Treat your pets regularly with high quality flea preventative all year round!