[4] The eastern copperhead is known to feed on a wide variety of prey, including invertebrates (primarily arthropods) and vertebrates.

Like most pit vipers, the eastern copperhead is generally an ambush predator; it takes up a promising position and waits for suitable prey to arrive.

Its generic name is derived from the Greek words ankistron "hook, fishhook" and odon, variant of odous "tooth".

[9][10] The trivial name, or specific epithet, comes from the Latin contortus (twisted, intricate, complex), which is usually interpreted to reference the distorted pattern of darker bands across the snake's back, which are broad at the lateral base, but "pinched" into narrow hourglass shapes in the middle at the vertebral area.

Brimley (1944) mentions a specimen of A. c. mokasen from Chapel Hill, North Carolina, that was "four feet, six inches" (137.2 cm), but this may have been an approximation.

[18] The eastern copperhead is found in North America; its range within the United States is in Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, Nebraska, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, and West Virginia.

In the Chihuahuan Desert of West Texas and northern Mexico, it occurs in riparian habitats, usually near permanent or semipermanent water and sometimes in dry arroyos (brooks).

In the Southern United States, copperheads are nocturnal during the hot summer, but are commonly active during the day during the spring and fall.

Unlike other viperids, they often "freeze" instead of slithering away, and as a result, many bites occur due to people unknowingly stepping on or near them.

[5] The eastern copperhead is a diet generalist and is known to feed on a wide variety of prey, including invertebrates (primarily arthropods) and vertebrates.

[18]: 128–130 p. [11]: 254–255 p. [23]: 181–184 p. Studies conducted at various locations within the range of the eastern copperhead (A. contortrix), including Tennessee,[24] Kentucky,[25] Kansas,[26] and Texas,[27] identified some consistently significant prey items included cicadas (Tibicen), caterpillars (Lepidoptera), lizards (Sceloporus and Scincella), voles (Microtus), and mice (Peromyscus).

Accounts of finding large numbers of copperheads in bushes, vines, and trees seeking newly emerged cicadas, some as high as 40 feet above ground, have been reported from Texas by various herpetologists.

[18]: 130 p. [28][29]: 347–348 p. Other items documented in the diet include various invertebrates, e.g. millipedes (Diplopoda), spiders (Arachnida), beetles (Coleoptera), dragonflies (Odonata), grasshoppers (Orthoptera), and mantids (Mantidae), as well as numerous species of vertebrates, including salamanders, frogs, lizards, snakes, small turtles, small birds, young opossums, squirrels, chipmunks, rabbits, bats, shrews, moles, rats, and mice.

[11]: 254–255 p. [23]: 181–184 p. Like most pit vipers, the eastern copperhead is generally an ambush predator; it takes up a promising position and waits for suitable prey to arrive.

One exception to ambush foraging occurs when copperheads feed on insects such as caterpillars and freshly molted cicadas.

[30] They possess facial pit organs which is a complex infrared-imaging system that allows accurate and precise strikes on potential prey.

[31] Juveniles use a brightly colored tail to attract frogs and perhaps lizards, a behavior termed caudal luring (see video: [1]).

These include: move away or flee, musking, tail vibrating, mouth gaping, or curling up into a camouflage pile.

[35] Their size apart, the young are similar to the adults, but lighter in color, and with a yellowish-green-marked tip to the tail, which is used to lure lizards and frogs.

This process leads to genome-wide homozygosity, expression of deleterious recessive alleles, and often to developmental failure (inbreeding depression).

[38] Copperhead venom has an estimated lethal dose around 100 mg, and tests on mice show its potency is among the lowest of all pit vipers, and slightly weaker than that of its close relative, the cottonmouth.

[39] Copperheads often employ a "warning bite" when stepped on or agitated and inject a relatively small amount of venom, if any at all.

[42] The venom of the southern copperhead has been found to hold the protein contortrostatin that halts the growth of cancer cells in mice and also stops the migration of the tumors to other sites.

Pain management, tetanus immunization, laboratory evaluation, and medical supervision in the case of complications are additional courses of action.