Humans have experienced great torment by pests. Pest control as we know it; is the…
Spiders have unfortunately earned a bad reputation like most other creatures such as scorpions and even snakes due to their perceived threat to people’s lives.
In Southern Africa, there are 64 of the 106 spider families known to occur worldwide, which represents approximately 3800 recorded species, and of these 3800 odd species, only 5 spiders are medically significant to humans!
What is a spider?
A spider is an arachnid and not an insect. They possess 8 jointed legs and not 6 legs as with an insect. They range in size in respect to their body length, ranging from tiny (less than 1.5 mm) to very large in size (more than 30mm). They are land-based predators, have external skeletons (exoskeleton) and moult/ shed their skins in order to grow. They possess two main body parts, an abdomen and cephalothorax with mouthparts in the form of two fangs. They have simple and compound eyes, with the majority of spiders possessing 8 eyes, with the exception of very few species that possess 6 eyes. Spiders rely mostly on touch and vibration as their main sensors in finding prey as most spiders have poor eyesight, apart from a few that do possess good eyesight, namely the very common small jumping spider.
Spiders lay eggs and unlike certain insects, they do not metamorphose in terms of their life cycle development. All spiders produce silk, with some species spinning small to very large elaborate webs, and other ground-dwelling and certain arboreal spiders laying a thin sheet of web to protect themselves, notably spiders that are free-roaming in nature. Other species line borrows underground with their silk, and others use silk to make retreats in spaces they find a suitable spot.
Silk is also used to wrap their eggs into a silken case, and spiders do use their silk to wrap their prey in it once caught, and most commonly seen spider webs are the harmless orb-web spiders that construct webs to ensnare flying or crawling insects that land or fall into the silken web.
Just about all spiders produce venom in order to kill their prey. The venom consists of a mixture of venom, saliva and digestive fluid.
As mentioned above of the over 3800 species in Southern Africa, only 5 are of medical importance to humans if they are bitten in this very unlikely event.
In general, most spider bites have little to no effect on larger mammals including humans, as the venom produced by the spider is there to kill its small-sized prey. Most human spider bites occur when a spider simply defends itself if a person accidentally harms a spider by either lying on it, or the spider getting harmed when it inadvertently gets into one’s clothing and gets harmed in the process.
When a bite occurs, it may hurt initially and then progress to being itchy for a number of days. If left without scratching and damaging one’s skin, it should disappear in a few days with no further effects. That is if the spider at hand is not one of the 5 medically important species we will touch on below.
At this point, it must be noted that a number of suspected spider bites turn out to be lesions caused from possible skin bacterial infections, and also other culprits causing this can be other biting insects such as ticks, fleas, mosquitoes or even bed bugs (you can read more here about how to identify those bites/stings). When a spider bite is suspected, it’s important to ascertain if there are two defined puncture marks, as this will show it as the spiders’ fangs having bitten the skin.
It is advised if you have any suspected bite, and symptoms of localised pain and swelling, redness and swelling of a bite site progress, along with extreme pain, nausea, vomiting, tremors, fever, numbness associated with such a bite, that you seek medical attention urgently, and most importantly if you can find the spider or responsible animal for the bite, that you either take it with or a clear picture so the medical experts can provide the best and quickest route for treatment.
1. Black button Spider (Latrodectus indistinctus)
The black button spider is considered South Africa’s most dangerously venomous spider. It is identified by the larger female spiders being a dark black colour, with a large abdomen with a distinctive red or red/gold coloured marking on their abdomens on the upper side, with some specimens having either a red dot or a red strip under their abdomen. South African black button spiders do not possess an hourglass marking on the tip of their abdomen. These are often mistaken for the American black widow spider. Any widow spider with an hourglass marking on it would be a subspecies of our brown button spider. Black button spiders also create smooth round egg sacs that the females contain within their webbing.
Their venom is a powerful neurotoxic venom, however, they will not bite when provoked, but would rather curl up into a ball when encountered. If bitten and you positive of the identification as a button spider bite, seek medical attention as antivenin is available at selected hospitals.
2. Brown button spider (Latrodectus geometricus)
The brown button spider ranges in colour from a lighter black, to brown and sometimes a creamy white with brown colouration forms. This spider is the most confused as a black button/ widow spider in South Africa, as they possess an hourglass pattern shape just underneath the females’ abdomen. The hourglass marking is red to orange in colour. This spider is one of the most common venomous spiders in South Africa. It is indeed venomous, and similar to that of the black button spider, but less potent.
If the spider is positively identified if a bite occurs, medical attention should be sort if symptoms develop that are similar to the neurotoxic black button spider bite symptoms. There have been very few cases where patients needed medical attention resulting from their bites, but it’s always best to be checked out by a medical practitioner especially if people are at high risk with underlying conditions or present allergic reactions. Antivenom is available for all species of button spider in South Africa, but no fatalities have been recorded as a result from a brown button spider bite.
3. Violin Spiders (Loxosceles species)
Violin spiders are confused with the recluse spider from the USA when people search on the internet for them. The Violin spider is not a recluse spider, and there are 3-4 species that occur in South Africa.
These spiders are free ranging spiders, nocturnal hunting spiders that do not construct permanent webs. They find refuge under rocks, logs, fallen wood and shelter during the day and spin a few strands of silk in the refuge as they rest. The silk is a white to a bluish colour.
Their venom is cytotoxic (causing tissue damage), but are very reluctant to bite even when handled, but will do so if they feel threatened in any way. Their bites can produce long lasting wounds that can swell up, and can range from a red to purple colour around the bite site that can spread in size if left untreated by a medical professional. The bite is not life threatening as been exaggerated on various social media posts and various links in the past. Medical treatment is done symptomatically based by a medical professional. Antivenom is not normally needed.
4. Sac Spider (Long Legged Sac Spider- Chericanthium species)
Sac spiders are small to medium-sized spiders with straw yellow to white coloured bodies with black mouthparts (fangs). It is one of the most common venomous spider found in South Africa. They are nocturnal free-ranging active hunting spiders. They rest during the day in white sac-like silk woven retreat of which they emerge to hunt at night. These are normally constructed outside in leaf litter, under logs, rocks, bar etc, but they can come indoors and construct such retreats in houses in between curtains, in cupboards etc. Due to their common habit of entering homes, this spider accounts for over 75% of known spider bites in South Africa. The bites of the spider produce small necrotic wounds which can take weeks to heal. The treatment is done symptomatically by a medical professional. The site of the spider bite should be left dry and not covered to assist in skin healing.
5. Six-eyed sand spider (Sicarius sp)
Six eyed sand spiders are only found in arid, dry semi-desert environments within South Africa. They are extremely difficult to find and are a species of a spider a person will very rarely ever encounter. In the arid areas of South Africa that they occur in, they seek shelter under the surface of the sand under the shelter of the entrances to caves, overhangs and under the shelter of rocks. They are a unique spider in possessing six and not eight eyes and have curled tufts of fine hairs on their abdomen and cephalothorax to allow sand to be lodged on the top side of the spider to aid in their camouflage. They have a powerful venom, which is both cytotoxic and haemotoxic, and a very unlikely bite from one of these spiders could cause tissue damage around the area of the bite, along with causing internal bleeding. There have further not been any human bites from this spider to understand the treatment required for such a bite.
It is not an aggressive spider, and there is a very little to no likelihood of one encountering this species of spider
A note about spider bites:
When a person is bitten by a spider, whether it falls into the above category of 5 medical important spiders or not, is the problem of when the bite occurs would induce itching, and this, in turn, causes the victim to scratch the bite site, which potentially results in secondary bacterial infection caused by one’s fingernails, especially if they are not clean when scratching and breaking the skin. The infection thus spreads and the lesion is solely blamed on the spider bite itself.
These are Guidelines to aid in the treatment of a proven cytotoxic spider bite. As we are not medical practitioners, we can only share some medical advice on what to do:
This would apply to the latter 3 spiders mentioned above (Sac spider, Violin spider and six-eyed sand spiders)
- There is no antivenin available for cytotoxic spider bites, so the first thing to do is to seek medical attention if you can confirm the bite is from one of the three spiders mentioned.
- The treatment provided by the medical practitioner is to promote healing and to limit any secondary infection.
- Keep the site of the spider bite clean and open. Do not cover it up or try any self-treatment until medical advice is sought.
- The medical practitioner will probably administer antibiotics and provide a Tetanus injection.