Fleas

Cat Flea (Ctenocephalides felis): Extremely common parasitic insect whose principle host is the domestic cat.  Adults of both male & female range from 1-2mm in length and are usually a reddish-brown colour.

Fleas go through four life cycles stages of egg, larva, pupa and adult.  Adult fleas must feed on blood before they can become capable of reproduction.

Adult fleas do not willingly leave their hosts and inter-animal transfer of adult fleas is rare except in animals that share sleeping quarters.  A flea which becomes separated from its host will often die with hours from starvation. 

Dog Flea (Ctenocephalides Canis): A species of flea that lives as an external parasite on a wide variety of mammals, particularly the domestic dog & cat.  The dog flea can spread Dipylidium caninum (Flea tapeworm or double-poured tapeworm). They feed on the blood of dogs & cats; they also bite humans.  They can live without food for several months, but females must have a blood meal before they can produce eggs. The female can deliver about 4000 eggs on the host fur. Like the cat flea has four stages of life; embryo, lava, pupa and adult. Depending on temperature this process can take 2-3 weeks.
The dog flea's mouthparts are adapted for piercing skin and sucking blood. The dog often experiences severe itching in all areas where the fleas may reside.

Fleas do not have wings and their hard bodies are compressed laterally and have hairs and spines, which makes it easy for them to travel through hair. They have relatively long hind legs for jumping.