Spiders:
Red Back Spider or Back Widow Spider
General Description
|
Credit: Laurence Grayson |
Credit: William |
- Adult female redback spiders usually have a body length of 10 to 15 mm long, while the male is much smaller, being only 3-5 mm long.
- The female is recognized by her spherical black body with a prominent red stripe on the upper side of her abdomen and an hourglass-shaped red/orange streak on the underside.
- Males are light brown, with white markings on the upper side of the abdomen and a pale hourglass marking on the underside.
- Occasionally, markings or the female black abdomens may occur.
- The cephalothoraxis much smaller than the abdomen, and is black.
- Redback spiderlings are grey with dark spots and become darker with each molt.
- Juvenile females have additional white markings on the abdomen.
- The bright scarletred colors may serve as a warning to potential predators.
- The spider has a pair of venom glands, one attached to each of its chelicerae with very small fangs.
Life Cycle and Common Characteristics
- The female black widow spiders take about 2-3 months to mature.
- After mating the females kill the male.
- Females lay eggs and create egg sacs (each containing up to 300 eggs) to keep them safe in. Most of the hatchlings do not survive because they are eaten by their siblings or by wasp parasitism.
- The young spiders hatch from the eggs after 8 days and emerge from the egg sac after 11 days of egg laying.
- After emerging the young from the eggs they mature for in 2-3 months, and molt 3-8 times until they reach adulthood.
- They build irregularly shaped webs that they rarely leave.
- Females may live for 2 to 3 years, whereas males only live for about 6 or 7
- Spiders reside in dark, dry areas such as logs or under rocks.
- Spiders are carnivorous eating small insects that are caught in their webs. They also eat skinks and juvenile mice, snakes, and frogs.
Damages and Economic & Medical Implications
- Only female redback widow spiders are venomous. Males are hardly seen and are completely harmless to a person.
- The venom affects the nervous system of the victim. Symptoms of poisoning occur quickly and include shock, chills, stomach cramps, fever, nausea, headache, high blood pressure, difficulty breathing, and sweating.
- One has to be careful when picking up waste, as he rarely feels its sting, but he realizes it recently when the wound site is swollen and two small spots appear at the site of the fangs penetrating the skin. The sting pain is excruciating and runs throughout the body, especially the legs.
- The bite of this spider is serious but rarely leads to death.
- Most bite victims fully recover within two days.
- Redback widow spiders are also beneficial spiders because they help to keep populations down of other spider species and nuisance insects by feeding upon them.
