Spiders inside your home? Vanessa explains why some can be 'great allies'

While arachnids represent a real threat to pets and animals, the risk of humans dying as a result of a spider bite nowadays is quite low. In fact, there have been no deaths recorded in the country since 1979. And spiders can even be great allies against mosquitoes and cockroaches as a doctorate student at Macquarie University explains.

Vanessa Penna Gonçalves is a Brazilian biologist who is completing her PhD on arachnids at Macquarie University, in Sydney. Credit: Vanessa Penna Gonçalves

Key Points

• There have been no deaths from spider bites in Australia since 1979.
• Spiders work as 'pest controllers' against mosquitoes and cockroaches.
• Using chemicals to kill spiders can be inefficient and dangerous, says expert.

Australia is famous for its landscapes, hikes, beaches, surf spots and of course, animals with the ability to cause serious injury and death.

The country's potentially dangerous fauna are well known, and include snakes, crocodiles, sharks, jellyfish and even the platypus has venom capable of killing small animals and causing excruciating pain in humans.

For many, the most terrifying are spiders, and they may appear in places that humans frequent, including green spaces, balconies, and bins with their tell-tale webs even detected on the rear-view mirror of your car.

Portuguese version: 'A aranha tem mais medo de você que você dela', diz especialista brasileira

So, should we be worried? Are they as dangerous as we think?

A wolf spider that thinks it's a water spider. Credit: ROBERT WHYTE/PR IMAGE

To answer these questions, SBS Portuguese spoke with a Brazilian biologist who is completing her PhD on arachnids at Macquarie University, in Sydney.

'No death since the 1970s'

Vanessa Penna Gonçalves stresses that, although most human encounters are with harmless spiders, we cannot forget that Australia is home to the most dangerous species in the world, such as the funnel-web and the redback.

"There has been no record of death as a result of (spider bites) since 1979 when anti-arachnid serum or anti-venom began to be administered," Ms Gonçalves said.

"Accidents still occur and the availability of anti-venin is well distributed in Australia and you will find it in hospitals."

Vanessa Penna Gonçalves in her laboratory at Macquarie University, in Sydney. Credit: Vanessa Penna Gonçalves

If a human is bitten by a dangerous spider, the researcher explains: "It is important to keep calm, to place an ice pack on the bite and go to the nearest hospital."

Living in Australia requires becoming informed about spiders, including where they live and when they may appear, she says.

What to do when you find a dangerous spider in your home

According to Ms Gonçalves, spiders are a part of everyday life in an Australian household, and we should "take advantage of that".

It is impossible to live in Australia and not have huntsmen or house spiders.

Vanessa Penna Gonçalves

"These spiders perceive the world through vibration. When you get close to them, they know that you are much bigger and will not attack you," she said.

"They are more afraid of you than you are of them."

In fact, she says that arachnids tend to avoid being in places where humans are.

"The tendency is to always hide behind the curtains or the sofa, in darker places," she said.

"Spiders don't have eyelids like us, so they (can't) open and close their eyes (therefore) sunlight is uncomfortable and they also hide for defence.

"If you find a dangerous spider at home, try to remain calm.

"Try to collect the spider in a jar and take it to the Australian Reptile Park. They will extract the venom to produce anti-venom and this procedure can only be done with live spiders."

Allies against mosquitoes and cockroaches

Ms Gonçalves suggests that spiders can be "great allies" against other insect species, such as mosquitoes and cockroaches.

Spiders work as great pest controllers

Vanessa Penna Gonçalves

"Cockroaches cause diseases because they have various bacteria and viruses in their bodies, as they travel in sewage, over dead animals, etc., and can contaminate the kitchen or bathroom," Ms Gonçalves explains.

"Every now and then we have problems with diarrhoea, and we don't know where it comes from.

"Many times, it is because we have had contact with a surface contaminated by roaches. And spiders really like cockroaches because they are very fleshy.

“They trap mosquitoes as well, and some mosquitoes also carry diseases, in addition to being annoying."

Still not convinced? Here’s how to keep spiders out

Despite Ms Gonçalves’ arguments, a move to allow spiders to flourish inside your home may remain far off.

Vanessa Penna Gonçalves in a giant spider installation at the Natural History Museum, Berlin. Credit: Vanessa Penna Gonçalves

The Macquarie University researcher says the best options for keeping arachnids outside are the mechanical ones, not chemicals.

"The best way to prevent spiders from entering your home is to close access," she said.

"They enter through door and window openings.

"I advise people to install door seals and close all possible holes.

"Here in Australia, older houses have some holes in the wall that connect them to the outside. Air conditioning gaps between the equipment and the wall are also an opportunity for them to enter."

It might not be the most efficient, but Ms Gonçalves said she would not recommend the chemicals.

"There is even a campaign called ‘No Spray Spring’ to make people aware that it is not a good choice," the biologist said.

"Firstly, most insecticides are not directly developed for spiders.

"If you spray directly on the spider, it will die of course. But, with pest control in the house, the poison particles will end up getting stuck in the hair that they had on their legs, which won’t kill them."

She warns about the extra danger for humans living in the house.

"Insecticides are also very harmful to us," she said.

"In addition to destroying the ecosystem in your home, they can also cause respiratory problems."

Who to call if bitten

• If unsure what to do after a spider bite, call the nationwide Poisons Information centre helpline on 13 11 26.
• For all snakebites and any case of emergency, call triple zero (000).
• If you are far from a hospital, you can call the Royal Flying Doctor Service on 1300 My RFDS (1300 69 7337).