The cat flea (scientific name Ctenocephalides felis) is an extremely common parasitic insect whose principal host is the domestic cat, although a high proportion of the fleas found on dogs also belong to this species. This is despite the widespread existence of a separate and well-established "dog" flea, Ctenocephalides canis. Cat fleas originated in Africa but can now be found globally. As humans began domesticating cats, the prevalence of the cat flea increased and it spread throughout the world.
Of the cat fleas, Ctenocephalides felis felis is the most common, although other subspecies do exist, including C. felis strongylus, C. orientis, and C. damarensis. Over 90% of fleas found on both dogs and cats are Ctenocephalides felis felis.
Overview
The cat flea belongs to the insect order Siphonaptera which in its adult stage is an obligatory hematophage. Adults of both sexes range from 1–2 mm long and are usually a reddish-brown colour, although the abdomens of gravid females often swell with eggs causing them to appear banded in cream and dark brown. Like all fleas, the cat flea is compressed laterally allowing it to slip between the sometimes dense hairs of its host just above the top layer of the skin, resulting in an extremely thin insect that may be difficult to observe even if the host's coat is pure white. Cat fleas are wingless.
The cat flea affects both the cat and the dog worldwide. The cat flea can also maintain its life cycle on other carnivores and on omnivores, but these are only chosen when more acceptable hosts become unavailable. Adult cat 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 within hours from starvation. It has been found that mortality differs between male and female cat fleas when separated from the host. It was found that within two days all male cat fleas were dead, while females became inactive after three days.
In addition to their role as pests in dogs and cats, cat fleas are responsible for a number of diseases. They can cause flea bite dermatitis and the transmission of dog tapeworm to name a few.
Life cycle
Cat fleas are holometabolous (undergo complete metamorphosis) insects and therefore go through four life cycle stages of egg, larva, pupa, and imago (adult). Adult fleas must feed on blood before they can become capable of reproduction.
Flea populations are distributed with about 50% eggs, 35% larvae, 10% pupae, and 5% adults. Cat fleas may live up to two years.
Eggs
An adult gravid female flea that has consumed a full blood meal will begin to produce between 20 and 30 microscopic (0.5 mm) non-adhesive white ovoid eggs per day, laying them individually and continually at a rate of about one per hour until she dies (under ideal conditions it might be possible for her to produce between 2,000 and 8,000 eggs in her lifetime, though most only manage to produce around 100 before being consumed by their host during grooming activity). The eggs are dispersed freely into the environment. Within two to seven weeks a certain proportion will then hatch into larvae. Hatching is at its highest when temperature is 27 °C and humidity is greater than 50%.
Given that eggs are non-adhesive, they do not stick to the host (70% are lost from the host in the first 8 hours).
Larvae
The larva of the cat flea has a grub-like appearance and is ~2 mm in length. The larvae are negatively phototaxic/phototropic, avoiding light and hiding in the substrate around them. The larvae require adequate ambient moisture and warmth, and will die at temperatures near freezing. Cat fleas prefer soil moisture content between 1-10%. While in this developmental stage the larvae will feed on a variety of organic substances, but the most important dietary item for them is the crumbs of dried blood that continually fall like snow out of the haircoat of the host after it has been excreted by the adult fleas as fecal material. Thus, the adult flea population continually feeds the larval population in the animal's environment. Adult feces is an important part of the larval diet. When reared in the lab, flea larvae provided with adult feces have a higher survival rate (67%) than those provided diets of dried bovine blood (39%) or meat flour (55%).
