and though they may be named from their principal host they often attack man and other animals indiscriminately. Many are worldwide in distribution. The Cat and Dog Fleas, Cteno-cephalides felis (Bouché) and C. canis (Curtis), often occur in houses where these animals are kept and may attack man; the Dog Flea serves as the intermediate host of a dog tapeworm. Cat and Dog Fleas possess both genal and pronotal combs (pronotal comb is a row of strong spines on posterior margin of pronotum). The Human Flea, Pulex irritans Linn., and the Rat Flea, Xenopsylla cheopis (Rothschild), lack genal and pronotal combs; both attack man and other animals.

The most important flea-borne disease is bubonic plague, transmitted chiefly by the Rat Flea; this is primarily a rodent disease but occasionally occurs in man, sometimes in epidemic form. Plague infection usually occurs at the time of biting, but may also result from the ingestion of an infected flea or by scratching its feces into the skin.

BAT FLEAS Family Ischnopsyllidae p. 311

Identification: Parasites of bats. Genal comb present and consisting of 2 or 3 broad lobes on each side. Head elongated. Eyes absent or vestigial. Some or all of abdominal terga 2-6 with 2 rows of bristles.

This is a small group whose members are not often seen.

STICKTIGHT and CHIGOE FLEAS Family Tungidae Identification: The 3 thoracic terga together shorter than the 1st abdominal tergum.

The most common species in this group is the Sticktight Flea, Echidnophaga gallinacea (Westwood), an important pest of poultry; it also attacks other birds and mammals. Adults usually occur on head of the host, often in dense masses, and remain attached for long periods. This insect is more common in the southern states. Another member of this family occasionally occurring in the southern states is the Chigoe, Tunga penetrans (Linn.); females burrow into the skin of man and other animals, usually on the feet. Males and newly emerged females of the Chigoe live much like other fleas, and feed on various hosts; the females burrow into the skin of man and other animals after mating. Once under the skin, the female's abdomen becomes greatly distended, and the surrounding tissues of the host swell to form a boil-like sore.

RODENT FLEAS Family Dolichopsyllidae Identification: Some or all of abdominal terga 2-6 with 2 rows of bristles (if these terga bear only 1 row of bristles, eyes are absent or vestigial and there is no genal comb). Genal comb usually absent, but if present consists of 3 or more narrow lobes on each side. Pronotal comb present. No suture on dorsal surface of head between antennae.

This is a large group whose members are chiefly parasites of rodents; a few attack birds, and one of these is sometimes a pest of poultry. Some fleas in this family act as vectors of bubonic plague but they generally transmit the plague from one rodent to another and are not important as a vector of plague to man.

RAT AND MOUSE FLEAS Family Hystrichopsyllidae

Identification: Similar to Dolichopsyllidae, but usually with a suture on dorsal surface of head between antennae, a genal comb, and 2 or 3 rows of bristles on anterior part of head.

This is a small family whose members are parasites of rats, mice, and shrews.

MALACOPSYLLID FLEAS Family Malacopsyllidae Identification: Some or all of abdominal terga 2-6 with 2 rows of bristles. Pronotal and genal combs absent. Clypeal tubercle (in middle of front part of head) well developed and somewhat pointed. 1 long bristle on each side of next to last abdominal segment.

This group is represented in the U.S. by 2 species of Rho-palopsyUtcSf which are parasites of opossums and rats. They occur from Georgia and Florida to Texas.

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