Spiders: Intimidating Intruders or Harmless Housemates?

Let’s face it – spiders aren't the most popular critters going around. Even among nature lovers, there are still a lot of arachnophobes. Arachnophobia is one of the most common fears, with estimates ranging from 3% to 30% of the population being affected. One study, done on 118 undergraduate students in the UK, found that a whopping 75% were mildly or severely afraid of spiders.  

The reason why arachnophobia is so prevalent may be because it has been ingrained in our biology through adaptive evolution – it pays to avoid things with deadly bites. Alternatively (or additionally), those who fear spiders may have been conditioned to do so from an early age (for example, if they have a parent who is an arachnophobe).

But whatever the reason, a lot of Aussies will say it’s a good thing to be afraid of spiders. They are the most widely distributed venomous animals in Australia, and yes – some of our species are deadly. But in reality, the vast majority of spiders pose little danger to humans and, as a whole, cause less deaths than snakes, sharks, bees, and even horses. Avoiding (or even killing) everything with eight hairy legs might be a bit of an overreaction. So, we thought we would compile a list of some of the most common spiders you are likely to see in the Greater Melbourne area and provide you with some insights into the scary – and not so scary – aspects of their biology.

Not as bad as you may think:

Huntsman

Image: Museum Victoria

Image: Museum Victoria

There are several species of huntsman around Melbourne and, if you’re not a fan of spiders, it’s unlikely you’d be super excited to find one of these guys camped out in your house or running across the dashboard of your car. But before you freak out and run a red light, remember that huntsman spiders are actually extremely timid. They are probably much more afraid of you! If you’re unlucky enough to get bitten, you’ll likely only experience a bit of discomfort and swelling because their venom is not very harmful to humans (but they do cause a lot of car accidents).

On the plus side, huntsmans can help maintain some of those other unwanted visitors in your home. They are visual predators with incredible eyesight that hunt for various creepy crawlies at night. They’re extremely quick and excellent at scaling vertical surfaces in search of a meal, such as insects like cockroaches that are often on the menu. So really, what’s not to love?

Garden orb weaver

We get a lot of orb weavers in my garden in inner city Melbourne - the telltale sign being the large, intricate webs they build to catch flying prey. They build these overnight, meaning unexpected encounters with humans doing a quick morning trip to the clothesline are common. But if this happens to you, never fear! The orb weaver’s bite is not dangerous, generally resulting in a localised reaction, so the worst that will happen is that you’ll have ruined the efforts of a poor spider’s all-nighter. Amazingly, the orb weavers in my backyard have begun to build their webs just above head-height to stop us messing up their hard work!

Image: Wikimedia Commons

Image: Wikimedia Commons

Daddy-long-legs spider

You may have heard that the daddy-long-legs spider has the most poisonous venom of any spider – I remember when the rumour spread around my primary school – but there is no scientific evidence to support this. The venom of daddy-long-legs actually isn’t even that toxic to insects. The second part of the urban legend says that daddy-long-legs can’t inflict their supposedly extremely harmful venom on humans because their fangs are too tiny, but this has also been proven false. All the same, it’s very unlikely you’ll receive a bite from these guys, and if you do it’s probably nothing to worry about. What’s more is that these spiders are excellent at catching other spiders in their webs. So rather than sweeping up their webs at will, consider that they may be keeping more potent spiders at bay!  

Where to be careful:

Redback spider

Image: Doug Beckers / Wikimedia Commons

Image: Doug Beckers / Wikimedia Commons

Redback spiders are one of the most venomous in Australia – but no deaths have been recorded since the discovery of the anti-venom in 1950. While red markings on the females make them easy to spot, colour morphs do occur, so be wary of black or brown spiders with that characteristic, pea-shaped abdomen and long, slender legs. While if you do get bitten you should get it checked out as soon as possible, don’t fear this species' presence around the home too much. The females (who are capable of harmful envenomation) generally build their webs in dark, secluded locations and are unlikely to move from them unless forced. Many bites occur when people unwittingly put their hands into a web, where a female may be defending her egg sack. So before you go fossicking around in areas out of view, consider that you might be intruding on a protective mother’s patch.

White-tailed spider

White-tailed spiders are excellent hunters that do not require a web to catch their prey. They’re particularly partial to feeding on black house spiders and will pluck at their victim’s web, mimicking the vibrations of an ensnared insect. When their victim rushes out to claim their prize, the hunter becomes the hunted. Bites from a white-tailed spider are relatively common as they are frequently found inside, often hidden amongst bedding or clothing left on the floor. Their venom in some cases can cause pain and swelling at the bite site as well as nausea. White-tailed spiders have previously been blamed for causing long-term skin infections (necrosis) that result from bacteria found around the spider’s fangs – and not the venom itself – but there is little scientific evidence to support this.

Still worried about a spider you might come across? Then check out this great spider resource from Museum Victoria. If you are ever bitten by a spider that cannot be identified with certainty, it is advised to contact a medical professional if a serious or long term reaction develops. 


Ella Kelly

Ella is a PhD Candidate at the University of Melbourne, where she spends a lot of time thinking about why some quolls don’t eat cane toads (if only she could ask them!). She also enjoys talking and writing about science, and would ultimately love to have an actual impact on the conservation of Australia’s biodiversity.

You can find her on Twitter at: @elkelly1210 

 


Banner image courtesy of David McClenaghan / CSIRO.