  The redback spider (Latrodectus hasselti), sometimes called the Australian black widow, is a species of highly venomous spider native to Australia, and can also be found in southeast Asia as well as New Zealand. The adult female redback is easily recognised by her spherical black abdomen with a prominent red stripe on the upper side, and an hourglass-shaped red or orange streak on the underside. Females usually have a body length of about 1 centimetre, while the male is much smaller, being only 3 to 4 mm long. The female has slender legs, with the first pair being longer than the rest. The bright red markings may serve as a warning to potential predators. The spider has a pair of venom glands, with very small fangs. 
The nocturnal female redback lives in an messy web in a warm sheltered location, often inside human residences. It preys on insects, other spiders and small vertebrates that become ensnared in its web. The redback wraps up its victim with silk, and kills its prey by injecting venom through its two fangs when it bites. The venom liquefies its victim's innards, which the spider then sucks out. A potentially dangerous victim may be left to struggle for hours until it is exhausted enough to approach safely. Male spiders and spiderlings live on the periphery of the female spider's web and eat leftovers. The female lays a clutch of about 250 eggs housed in a round silken egg sac.   The redback is one of the few spider species that can be seriously harmful to humans. Envenomation begins with pain around the bite site, which becomes more severe as it progresses up the bitten limb, and persists for over 24 hours. Symptoms of nausea, vomiting, headache, and agitation may also occur. An antivenom has been available since 1956. As the female redback is slow-moving and rarely leaves her web, bites usually occur as a result of placing a hand or other body part too close to the spider, such as when reaching into dark holes or wall cavities. Bites also occur when a hidden spider is disturbed in items such as clothes, shoes, gloves, building materials, garden tools or children's outdoor toys. 
The redback is mainly nocturnal. The female remains concealed during the day, and spins her web during the night, usually staying in the same location for most of her life. The web is an irregular-looking tangle of fine but strong silk. The threads seem random, but are strategically placed for support and entrapment of prey on the ground below. The vertical strands act as trip wires to alert the spider to the presence of prey. They snare and haul prey into the air. The individual web filaments are very strong, able to entangle and hold even small reptiles. Redbacks usually prey on insects, but can capture larger animals that become entangled in the web, including trapdoor spiders, small lizards, and even on rare occasion snakes. Developing spiderlings need size-appropriate prey, and they consume common fruit flies, mealworm larvae, flies and nymphs of cockroaches. 
Spiderlings can emerge from the egg sac as early as 11 days after being laid. Redback spiderlings live on the maternal web for several days to a week, during which time sibling cannibalism is often observed. They then leave by being carried on the wind. They climb to the top of nearby logs or rocks before extending their abdomens high in the air and producing a droplet of silk. The liquid silk is drawn out into a long thread that, when long enough, carries the spider away. This behaviour is known as ballooning or kiting. Eventually, the silken thread will adhere to an object where the young spider will establish its own web. Females mature in about 75 to 120 days. Males live for up to six or seven months, while females may live between two and three years. In about two out of three cases, the female fully consumes the male after mating. The black house spider and the cellar spider are known to prey on the redback spider, and redbacks are often absent if these species are present in significant numbers. 
Some of the pictures used on this page were obtained from Leo Henry's amazing YouTube channel leokimvideos. Leo is from Sydney, New South Wales in Australia, and spent many years studying the redback spider after finding that his back yard had become infested with them. He raised generations of the spiders in terrariums and was eventually able to successfully control them in his yard by predicting their behaviour. His spider videos are the stuff of legend, 'highly educational', and well worth watching from the beginning! |