My big bumper internet book of facts gives this insight into the life of this spider.

Argiope lobata (Araneidae)

Argiope lobata is a fairly large orb weaving spider. It weaves expansive webs, usually vertical, above ground level; this allows the spider to trap flying insects. One easily recognised sign of this type of spider is a visible zigzag of silk in the centre of the web. The spider often sits in the centre of the web where it can easily access prey which gets stuck in the web. Argiope lobata spiders pose with the head facing downwards and the legs are often in pairs giving the impression that there are only four.

The zigzag patterns are called stabilimenta and have been accredited with several possible functions including making the web more visible to avoid damage by passing animals or reflecting ultraviolet light which attracts insects. Once suitable prey has hit the web it is wrapped in silk to immobilize it and then bitten to be injected with venom. The venom paralyzes the victim while liquifying the inside of its body with protein dissolving enzymes. When the food parcel stops struggling the spider can suck out the juices and then discard the silk covered remains. If not eaten immediately the prey can be stored for later consumption. If the prey is too large to be eaten it is cut free from the web.

The adult female is around three times larger than the male. The male approaches the female when she has just completed her final moult. This is when she reaches sexual maturity but also a time when he is least likely to be eaten. Once mating is completed the male retreats. The female gradually expands - heavy with eggs - and around a month later she lays several egg sacs in the nearby vegetation.

The venom of this spider is not dangerous to humans. In the very unlikely case of a bite occurring there may be mild swelling and itching. This species is widespread almost everywhere in the world except the Americas.

Many thanks to mchportal.com