Explanation of Names
SIPHONAPTERA: from the Greek "siphon" (hollow tube) + "a" (without) + "pteron" (wing); fleas are wingless and have tube-like mouthparts for sucking blood
Numbers
275 species in 74 genera in 8 families in North America (
nearctica.com)
2,100 species worldwide
Size
1-10 mm but most are less than 5 mm
Identification
Adult: body dark, laterally flattened, wingless; hind legs adapted for jumping; mouthparts adapted for piercing skin and sucking blood; row of large bristles often present on head and/or thorax (called genal and pronotal combs)
Larvae: pale legless worm-like body covered with sparse bristles; head reduced, eyeless, with chewing mouthparts
Range
cosmopolitan; greatest species diversity in temperate zones
Habitat
adults are found on or near host but will vacate a dead host shortly after death and search for another
larvae are found in nest or bedding of host
Food
adults feed on the blood of mammals (about 90%) and birds (about 10%)
larvae feed on organic debris, including adult flea feces (which contain undigested blood), and dead mites
Life Cycle
Eggs are laid in the host nest, bedding, carpet, upholstery, or cracks in the floor, usually hatching in 7 to 14 days. After a larval period that includes two molts, fleas pupate within a thin silken cocoon. Under favorable conditions, the life cycle can be completed in less than a month. Most fleas spend a considerable amount of time away from their host. Adults may live for two years or more and can survive for weeks or months without a blood meal.
Remarks
The laterally-flattened body allows easy movement among the host's fur or feathers, and backward-pointing bristles of the hard cuticle prevent fleas from falling off or being easily captured by the host. Fleas may be extremely irritating to the host, causing skin inflammation and itching.
Fleas transmit pathogens that cause disease in humans and other animals. The Cat Flea and Dog Flea are intermediate hosts for a tapeworm (Dipylidium caninum) that infects dogs, cats, and humans. The Rabbit Flea spreads a myxomatosis virus within rabbit populations, and the Oriental Rat Flea is the primary vector of Yersinia (=Pasturella) pestis, the bacterial pathogen for bubonic plague.
The Cat Flea commonly infests dogs, and the Dog Flea may infest cats; both species may bite humans.
Fleas only infest animals that have a regular nest site, which is why most rodents (rats, mice, etc.) have fleas but most ungulates (cows, horses, deer, etc.) do not.
Some fleas can jump 200 times their body length.
Internet References
preserved adult image of Cat Flea (
Ctenocephalides felis) plus description, hosts, fossil history, evolution (U. of California at Berkeley)
adult and larval drawings plus description, biology, hosts etc. (John Meyer, North Carolina State U.)
description, biology, human history, legends and myths, proverbs (Gordon Ramel, earthlife.net)
