Spiders are so useful around the house! This one is a fairly common visitor to ours and it eats everything it catches in its web. I am always happy to see it munching away on a fat blow-fly in summer.
It is Badumna longinquus, the Australian Grey House Spider, although actually its only grey due to fine hairs that cover its abdomen. More a sort of raw umber brown with those warm reddish striped legs.
This one refused to stand still on its own identification page in my Crowe, and was much happier when it had slipped under the book and onto a branch of the wisteria.
Like its relative the black house spider B. insignis, it builds a rather messy nest, which sometimes gets bits and pieces stuck in it (not a reason for sweeping it away, I plead). When the webbing loses its stickiness these two spider species just seem to weave on a few more strands, usually at night. It's rather like a human house that's just been added onto as the family has grown. With a broken fence, a couple of old cars and a dead pear tree out the back, maybe.
Female Badumna are very shy to leave their homes and will be quite reluctant to vacate if you try to frighten them away. They will slip quickly back into their funnel-shaped room in the centre or back of their web, where there may also be a couple of cocoons of eggs or babies developing. Some of these babies may stay around and eat tiny midges and other food that may be too small to be noticed by the mother. It is unusual among spiders for the mother to share her home with her growing babies.
Badumna's main predator is the white-tailed spider, although I once read of a Badumna defending itself successfully and the white-tail beating a hasty retreat, with a limp, ha ha!
Most people, including farmers, probably don't realise how useful spiders are in eating insect species that would otherwise be a pest in our gardens and houses. It's hard to calculate the effect if all spiders were to be suddenly eliminated from the world, but the increase in pests would possibly be noticed within six hours!
Spiders are generalist feeders - meaning they eat anything, but they will eat more of those species that are very numerous, so they are very good at keeping populations from getting out of control.
Spiders are also very numerous themselves, and are able to go a long time without eating, so they are there waiting and hungry in spring when the pest insect numbers start to really take off. So don't kill them off in winter! Your vegetables will thank you!
The large numbers of spiders' offspring (and, indeed, that of all insects) provide an important food source for birds and other animals.
Here is a little information on a great Chinese study that helped to educate farmers about the importance of spiders and other insects to their crops. It also showed them the importance of providing 'rough' strips of uncultivated land on the borders of fields, and that pesticides killed off the beneficial species as well as the pests, and altered the ecological balance.