Redback Spider

Redback spiders are part of the same family as the Black Widow spider. This group of spiders is found throughout the world in one form or another. They vary in the amount of danger they are to people as not all of these spiders are as dangerous as the Black Widow.

Females

• Black to brown growing to approximately 12mm in body length.  
• A pea shaped abdomen with a scarlet or orange strip on the back which is often broken or outlines with fine white markings.
• The underneath of the abdomen has a characteristic orange/red marking in the shape of an hour-glass. Slender black-brown legs.

Males

• Redback spider males mature quickly, growing to a size of only 3mm in body length.
• Redback spider males do not lose the juvenile characteristics.
• Redback spiders are too small to bite us and so are not dangerous (there are only 2 recorded male bites in history).

Juveniles

• White and black in colouring often with elaborate patterns including lateral stripes (occasionally these remain into adulthood).
• Each time the spiderlings moult, they lose some of the juvenile characteristics and develop more of the adult colouring.

Habitat

• Favour rocky areas, logs, stumps and low shrubs as well as sheds, under flowerpots, garden furniture, outside toilets and even under broad-leafed vegetables.
• Funnel-type of retreat: in the upper part of a tangled network of silken threads. Funnel is in a sheltered area, away from sunlight, where it is well sheltered and warm.
• Redback spiders are very easily transported around the country. They or their egg sacs remain hidden in goods or on trucks and vehicles as they are transported. They have even spread to Japan hidden in crates.

Lifecycles Redbacks

• Redbacks reproduce rapidly in warm weather.
• The small male Redback spider mate twice with the same female during each season.
• They throw themselves onto her fangs after each mating, dying after the second time.
• This single session is sufficient to fertilise the eggs produced by the female for a period of 2 years.
• Female Redback spiders live for 2-3 years and during this time lay many thousands of eggs in sacs.
• The sacs are cream in colour and contain 40-500 eggs, and each time she lays she will produce 4-10 of these sacs.
• The spiderlings hatch in 2-4 weeks. The first to do so eat unhatched eggs and spiderlings before being dispersed by the breeze which blows the light spiderlings away attached to fine silken threads.

Danger

• Around 600 bites are recorded each year in Australia normally during spring and summer.
• Some, though not all result in serious pain and illness requiring anti-venom. The female has relatively small jaws often resulting in ineffective bites.

Treatment

• Anti-venom has been available for 50 years, and since its introduction there have been no deaths.
• Do not apply a pressure bandage for Redback spider bites as they can aggravate the pain. Because the molecules of the venom are large they can take hours to enter the bloodstream via the lymphatic system.
• Apply ice water to relieve pain.
• If a bite is suspected, seek medical attention.

Always try to catch the spider responsible and keep it for identification purposes