Fleas are a collective term for fleas, with 2500 known species worldwide and approximately 650 species in China. Fleas are small, wingless, and jumping parasitic insects; Flat on both sides of the body, brownish yellow to dark brown in color; The body wall is hard and has many manes, spines, and combs; The body is divided into three parts: head, chest, and abdomen, with distinct segmentation. Male fleas are usually smaller than female fleas. Flea larvae are small and slender, maggot shaped, milky white, without eyes or feet, with a body length of about 4.5 millimeters. Fleas are named after their ability to jump.

Fleas are widely distributed around the world, usually living on mammals and a few on birds. Fleas often move in dark areas, crevices, mouse holes, cat and dog nests, and other places. Flea larvae are extremely active, photophobic, and sensitive to dryness, feeding on certain organic debris in their living environment. Fleas are completely metamorphosed insects, and their life cycle goes through four stages: egg, larva, pupae, and adult; Female fleas mate by sucking blood and lay eggs in batches, which can last for several months. They produce about 300-500 eggs at a time, and it usually only takes one month for the eggs to develop into adults; The lifespan is about 1-2 years.

Fleas, both male and female, feed on blood and are sensitive to temperature. They can only parasitize when the host's body temperature is normal. If the host experiences an increase in body temperature or a decrease in body temperature after death, they immediately transfer to other hosts to feed on blood. Therefore, fleas on dogs, cats, and mice can all feed on humans. Fleas can cause the spread of many diseases, such as pestis, endemic typhus, tapeworm disease, subcutaneous parasitism, etc. Their habit of defecating while sucking blood has a great relationship with the spread of diseases. Human economic activities and transportation have made some flea species widely distributed worldwide.

The most common diseases caused by fleas are flea allergic dermatitis and flea bite dermatitis. Parasitic sheep exhibit severe itching and restlessness. Fleas have a large appetite, and an adult flea can inhale blood equivalent to 15 times its body weight in a day, causing individual production indicators such as physical weakness, weight loss, and decreased milk production in adult sheep, leading to poor lamb development. Long term parasitism by fleas can lead to anemia or blood borne diseases, such as brucellosis, which have a significant negative impact on the breeding and economic benefits of sheep. Fleas, both male and female, feed on blood and are sensitive to temperature. They can only parasitize when the host's body temperature is normal. If the host experiences an increase in body temperature or a decrease in body temperature after death, they immediately transfer to other hosts to feed on blood. Therefore, fleas on dogs, cats, and mice can all feed on humans.

Fleas not only pose a threat to animal health, but also pose new challenges to the quality of people's living environment and hygiene. Both male and female adult fleas have a blood sucking habit. After being bitten, it often causes local tissue allergies, resulting in papules of different sizes. Those with severe reactions may feel itchy and unbearable, and can also cause iron deficiency anemia.

Fleas are important vectors and can spread many important infectious diseases, including tapeworm disease, pestis, hemorrhagic fever with renal syndrome, endemic typhus and Bartonella disease. Fleas can cause the spread of many diseases, such as pestis, endemic typhus, tapeworm disease, subcutaneous parasitism, etc. Their habit of defecating while sucking blood has a great relationship with the spread of diseases. Human economic activities and transportation have made some flea species widely distributed worldwide.