Sensing From Inside the Cocoon

The flea, a blood sucking external parasite of man and his pets, is a small wingless insect. It is dark reddish brown or black, with the last pair of legs strong and modified for jumping. Its body is thin and covered with backwardly directed spines, most suited to move on the furry skin of pet animals.

The flea has piercing and sucking type of mouthparts. It bites the skin and sucks blood. Though it prefers the blood of pets, hungry fleas that have been starving for sometime, will attack humans too in leg and ankle areas, causing itching and rash. Its salivary secretions cause skin irritation.

The fleas are named after the hosts they parasitize. Ctenocephalides felis is the Cat flea, Ctenocephalides canis, the Dog flea, Pulex irritans, and the Human flea and so on.

The fleas hide in the fur of the skin and lay eggs. The eggs of Cat flea are oval in shape and white colored. They are 1/50 inch long. A single female may lay up to 800 eggs during its lifetime. The eggs drop onto mats, carpets, rugs, or beddings when the pet moves. The eggs are abundant in places where the pet stays most.

The larva that hatches out of the egg is 1/16 inch long. It feeds on fecal matter of adult fleas, fecal matter of pets, and house hold food particles. It molts and grows up to ¼ inch length. It is now ready to pupate. It spins a cocoon.

The cocoon is made of silk. It is slimy. Particles of debris become a part of the cocoon structure, as the cocoon is constructed. The completed cocoon is well camouflaged and lies undetected in the debris. Inside the cocoon, the larva changes into pupa. The pupa undergoes development into the adult flea in about a week. The Cat flea life cycle from egg to adult will get completed in 20 to 35 days under ideal conditions of temperature (85F) and humidity (85%).

The adult flea remains inside the cocoon until it detects a suitable host. The flea can sense the floor vibrations, air movement, odor and body heat of the host, from inside the cocoon. Once it makes sure that the host ( a Cat for example) is very close, it breaks the cocoon open, jumps onto the host body and disappears within the fur of the host.

The flea’s sensory apparatus is amazing. It can feel the surroundings from inside the cocoon. It can lie in waiting for as many as five months to get its first meal of blood.