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Viperidae

Two-lined Night Adder

Venomous

Causus bilineatus

Two-lined Night Adder
Causus bilineatus, (c) Robert Taylor, some rights reserved (CC BY)

The Two-lined Night Adder (Causus bilineatus) is a venomous snake in the Viperidae family, recorded in 4 countries.

If you are bitten

This is a venomous snake. Treat any bite as a medical emergency: stay calm, keep the bitten limb still and roughly level with the heart, remove rings and tight clothing, and get to emergency care immediately. Do not apply a tourniquet, cut the wound, apply ice, or try to suck out venom. Call your local emergency number or poison center.

Family
Viperidae
Danger
high

About the Two-lined Night Adder

Causus bilineatus is a species of venomous snake in the subfamily Viperinae of the family Viperidae. The species is native to southcentral Africa. There are no subspecies that are recognized as being valid.

Common names

Common names for C. bilineatus include lined night adder, two-lined night adder, and two-striped night adder.

Description

Adults of C. bilineatus have an average total length (tail included) of 30–50 cm (12–20 in), with a reported maximum of 65 cm (26 in).

The head is slightly distinct from the neck, while the snout is fairly long and tapering. Midbody there are 15–18 rows of dorsal scales that are weakly keeled and have a soft and velvety appearance. The ventral scales number 122–141 in males and 128–144 in females. There are 18–30 subcaudals.

The color pattern consists of an ash to auburn to brown ground color, overlaid with numerous irregular or vaguely rectangular black dorsal patches. These patches lie within two distinct and narrow pale stripes that run the length of the body. The belly color is dark to dark cream.

Geographic range

C. bilineatus is found in Angola, southern DR Congo, Rwanda, western Tanzania, and Zambia.

The type locality is given by Boulenger (1905) as "between Benguella and Bihé" (Angola). Bocage (1895) listed "Duque de Bragança, Quissange, Caconda, and Huilla" (Angola) for the localities.

Habitat

C. bilineatus occurs in moist savanna, forest-savanna environments, and swampy habitats, at altitudes of 800–1,800 m (2,600–5,900 ft). Wild-caught specimens found to have eaten clawed frogs, Xenopus, suggest a more aquatic nature than other species.

Diet

C. bilineatus preys mostly upon toads and frogs, particularly the frogs of the genus Xenopus.

Reproduction

C. bilineatus is oviparous.

Venom

C. bilineatus is venomous, and there is no available antivenom. However, no human fatalities from its bite have been recorded.

Adapted from Wikipedia, available under CC BY-SA.

Frequently asked: Two-lined Night Adder

Is the Two-lined Night Adder venomous?
Yes. The Two-lined Night Adder (Causus bilineatus) is venomous and belongs to the Viperidae family (viper). Its bite is considered high risk to people. Treat any bite as a medical emergency.
Is the Two-lined Night Adder poisonous?
Snakes are venomous, not poisonous. "Poisonous" means harmful to eat or touch; "venomous" means injecting toxins through a bite. The Two-lined Night Adder is venomous, delivering venom through a bite.
Is the Two-lined Night Adder dangerous?
This is a venomous snake. Treat any bite as a medical emergency: stay calm, keep the bitten limb still and roughly level with the heart, remove rings and tight clothing, and get to emergency care immediately. Do not apply a tourniquet, cut the wound, apply ice, or try to suck out venom. Call your local emergency number or poison center.
Where does the Two-lined Night Adder live?
The Two-lined Night Adder has verified records in 4 countries, including Congo, Democratic Republic of the, Angola, Zambia. See the distribution section below for its full range.
What does the Two-lined Night Adder eat?
C. bilineatus preys mostly upon toads and frogs, particularly the frogs of the genus Xenopus.
Why is it called the Two-lined Night Adder?
Common names for C. bilineatus include lined night adder, two-lined night adder, and two-striped night adder.

If you are bitten by the Two-lined Night Adder

A venomous snakebite is a medical emergency. Call your local emergency number immediately. In the US, dial 911 or Poison Control at 1-800-222-1222.

Do

  • Get away from the snake and stay calm. Most bites worsen when people panic or try again to handle the snake.
  • Call 911 or Poison Control (1-800-222-1222) right away. Antivenom works best when given early.
  • Note the time of the bite and, from a safe distance, the snake's color and pattern, a phone photo is enough. Do not chase it.
  • Keep the bitten limb still and at roughly heart level. Sit or lie down and limit movement.
  • Remove rings, watches, and tight clothing near the bite before swelling starts.
  • Gently wash the bite with soap and water and cover it with a clean, dry dressing.

Do not

  • Do not cut the wound or try to suck out the venom.
  • Do not apply a tourniquet or ice.
  • Do not drink alcohol or caffeine.
  • Do not take aspirin or ibuprofen, they can worsen bleeding. Acetaminophen is safer for pain.
  • Do not try to catch or kill the snake. A dead snake can still bite by reflex.

First-aid guidance adapted from the U.S. Centers for Disease Control and Prevention (CDC NIOSH), Venomous Snakes. Educational only; always follow the instructions of emergency responders.

Where it is found

Congo, Democratic Republic of theAngolaZambiaZimbabwe

More Viperidae snakes

Classification

How scientists group this snake, from the broadest category down to the exact species. Each step narrows to its closest relatives.

OrderThe broad group of scaled reptiles: all snakes and lizards
Squamata
FamilyA group of related snakes that share key traits
Viperidae
GenusA close-knit group of very similar species
Causus
SpeciesThis exact snake, named in the two-part scientific name
Causus bilineatus

Keep learning

Distribution from GBIF & iNaturalist. Venom status per CDC. Background: Wikipedia. Informational only. Never handle a snake to identify it.