Spiders - Friend or Foe?

We all know them. Generally associated with burning houses down and horror stories – spiders have a poor rapport. I’ve seen grown men fall off exercise bikes backwards in fear of these eight-legged invertebrates. What is it that strikes such fear into the biggest and bravest of us? Is it their hairy little bodies? The compound eyes? The chitinous jaws? Or maybe it has to do with them dropping in unannounced and uninvited? They are found in most habitats and do well in the urban environment. Why? Because we have provided crevices in which to hide and gardens in which to hunt. Classed under Arachnids, spiders are, in fact, not insects but arthropods (meaning jointed legs) and there are 40 000 different kinds of them worldwide. 

We have all heard the dangerous versus not dangerous spiel, but for those of you that are unfamiliar – some spiders found in your backyard are venomous (not poisonous). They produce venom to kill their prey not you. Now let us be very clear here: venom is costly to make, it takes a lot of energy and is not used lightly as it takes time to remake, meaning they go hungry while they wait. So why would they waste it on you unless they felt their little life was in peril? Secondly, spiders want as much to do with you as you want to do with them – that is – nothing. You’re big, scary and make the ground vibrate, which for those that use web vibrations to hunt, must be quite noisy and intrusive. So, if you find yourself being bitten, take a moment to reflect on this, and then skedaddle, possibly to the hospital. 

Generally, spiders are obligate carnivores, but they are also classified as generalist feeders – that means they are a gardener’s best friend. Why? Because they are biological control agents. What does this mean? Free pest control, pesticide free existence and an all-round healthier space for both you and the rest of the creatures that share your living space. Don’t believe me? Read Silent Spring by Rachel Carsen. Spiders all hunt differently, at different times, for different periods. Pest species have also been known to disperse (as in run-away) when spiders are in the area. Some spiders ambush, others set traps, some during the day and the rest at night. So why do you have a pest problem? Because you keep killing the spiders, you muppet. 

I cannot deny that some spiders are dangerous, but only if you interfere with them. The following don’t mess around and should be avoided or safely relocated - NOT SQUASHED with a shoe. Every creature has a right to existence and although we don’t like to think about it, we humans are just as much part of the surrounding ecosystem as our segmented friends, therefore coexistence is key. 

Black button spiders (Latrodectus mactans) are shy and rare: They’re black with bright red patterns on the dorsal abdomen. Venom is highly neurotoxic- don’t pass begin, go directly to hospital for immediate medical assistance with anti-venom in extreme cases. They generally only attack if their nest is threatened, like the time I was cleaning a wildebeest skull. She came at me with murder on her mind because that skull harboured her eggs. I swear she ran up that jet of water I propelled from the hose in a last-ditch attempt to save myself. I made it out by the skin of my teeth after chucking everything in the air, including my dignity. Brown button spiders (Latrodectus geometricus) are more commonly found and have the same habitat preferences as their dark cousins. They’re brown with banded legs, and their abdomen varies from cream to black. If disturbed they will retreat, or fall to the ground, but don’t be fooled, they will bite when picked up. Spiders only bite when hurt. Their venom is neurotoxic, and bites will be very painful. The venom is less lethal than that of Black button spider. One currently resides in my Panda ear pot plant. She does not like Pina coladas or getting caught in the rain.

Sac spiders (Cheiracanthium inclusum) are medium in size and straw-coloured, with blackish mouthparts and dark eyes. Their front legs are the longest of all their limbs. They’re often found in plants, and dark corners of houses. Sac spider venom is cytotoxic and bites can be extremely painful, but it does not have the enzyme to cause any skin lesions. I once witnessed a professor fling a sac spider onto an unsuspecting spectator when he thought it was going to bite him. Chaos ensued as a hundred first years fled the veld screaming. Sac spider 1 – conservation students 0. 

Violin spiders (Loxosceles reclusa) don’t build webs. They also do not occur within 100km of Cape Town, but have been found under stones, in caves and dark areas and next to my bed when I lived in the Karoo, rubbing her forelimbs together in the middle of the night. They are meant to scatter when confronted. Needless to say, some strong words were said, and we did not part as friends.

On a less threatening note, Rain spiders are often found ominously splayed in the corner of a ceiling, especially when it rains. They’re brown with light and dark bands on the underside of their legs. This docile (as in calm) spider feeds on insects and small vertebrates, like geckos, not children. They can bite if aggravated, so leave alone or get the braver spouse to relocate. 

Daddy Long Legs (Smeringopus natalensis) A common spider in the house, shed or garage. They are small with very long thin legs spread out as if constantly seeking balance. Despite the myths, these spiders are completely harmless to humans and pets and don’t possess strong venom. They hunt insects in the house, like flies and mosquitos!

Flower Crab Spider (Thomisus kalaharinus) A small, pretty spider that comes in a variety of colours. They are fantastic ambush hunters. You generally find them sitting on flowers in the garden or out in the veld where they match the colour of the flower, but occasionally you will find a yellow spider on a white flower or the other way around. These spiders are harmless to humans and pets and hunt small pollinating flies, bees and wasps.

Jumping Spider (Thyene ogdeni) These small, charismatic spiders are commonly found around the house as well as in the garden. They don’t build webs, but use strands of butt silk like parachutes, catching breezes from one side of the garden to the other. They feed on flies and mosquitoes and a range of other small insects even though they are smaller than a pea. They are quite intelligent, visibly calculating the distances between objects they want to jump to when hunting. These spiders can jump about 30cm. They cannot bite people or pets and are great to have around the house to control insects. They also dance to woo their mate, waving their bums in the air like they just don’t care – how can you not be enchanted?

This is where my ecological rant ends. What would I like to achieve here? Curiosity. I want you to think first and act later. Knowledge is power here muchachos and conservation starts at home.

Clockwise from Top left: A pink flower crab spider (Thomisus kalaharinus) on the Lavender (Lavendula dentatas); A brown widow set up house in my Panda Plant (Kalanchoe tomentosa); A teeny jumping spider (Thyene ogdeni) contemplates its existence from the safety of a sunflower (Helianthus); another pink crab spider and last but not least, an African masked spider (Thomisus kalaharinus) steals himself a tasty bee snack.

About the author

Ashleigh McDonald is a bonafide conservationist and budding scholar. Currently completing her honours in Marine Biology, she worked in the veterinary industry for nearly a decade prior to taking the academic road less travelled. She resides with her fiance in the family home and is a few cats short of crazy cat lady status!