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Leeches: Hirudinea

North American Medicinal Leech (macrobdella Decora): Species Accounts

Physical characteristics: The North American medicinal leech grows up to 3.9 inches (100 millimeters) long and 0.39 inches (10 millimeters) wide. The upper surface of the body is olive with a row of orange spots down the middle. The underside is orange. An arch of ten eyes is arranged in five pairs. Each of the three jaws has very fine small teeth.


Geographic range: This species is found in Eastern North America, from southern Canada to the Carolinas and along the Mississippi River drainages.

The North American medicinal leech is found in naturally occurring freshwater lakes, ponds, streams, and marshes. It is usually found at the water surface near shore when at rest. (Illustration by Bruce Worden. Reproduced by permission.)

Habitat: This leech is found in naturally occurring freshwater lakes, ponds, streams, and marshes. It is usually found at the water surface near shore when at rest.


Diet: The North American medicinal leech feeds mostly on amphibian and fish blood, but occasionally attacks mammals. Blood meals are stored in the body up to several months.


Behavior and reproduction: This species is an excellent swimmer. They can detect prey up to several yards (meters) away by following waves in the water.

Sperm is deposited directly into the female reproductive organs of the mate. Up to ten or more eggs are laid in the cocoon. The cocoons are deposited on land near the edge of a body of water.


North American medicinal leeches and people: The North American medicinal leech was used in creation mythology of the Osage tribe of Native Americans. It was not widely used for blood-letting. This species was also seen in the film Stand by Me.


Conservation status: The North American medicinal leech is not considered threatened or endangered. ∎

Additional topics

Animal Life ResourceMollusks, Crustaceans, and Related SpeciesLeeches: Hirudinea - Physical Characteristics, Habitat, Diet, Behavior And Reproduction, Leeches And People, North American Medicinal Leech (macrobdella Decora): Species Accounts - GEOGRAPHIC RANGE, CONSERVATION STATUS