There is a widespread and surprisingly uniform set of assumptions and "general knowledge" that people have about spiders. And with very few exceptions, all of this widespread information about spiders is false! Here are the top 10 biggest myths.
The myths dealt with below are mainly North American. Some of the spider myths of other continents may differ.
1.) Myth: The daddy-longlegs has the world’s most powerful venom, but fortunately its jaws (fangs) are so small that it can’t bite you.
That is a full-fledged Urban Legend, with no basis in fact whatever. This legend is so widespread that many people believe it who should really know better, including some teachers and TV documentary producers.
Three different unrelated groups are called "daddy-longlegs." Harvestmen have no venom of any kind. None at all! Same with crane flies. Pholcid spiders have venom (like almost all spiders) but there’s nothing special about it; in fact, a recent study showed that pholcid venom is unusually weak in its effect on insects.
2.) Myth: Spiders are insects.
Actually, not everyone believes this. Around half of my callers did learn in school that spiders are not insects, but I find it rather appalling that the percentage is not higher. And how often, in mass media, we read or hear a phrase like "spiders prey on other insects!" Anyway, spiders belong to the Class Arachnida, insects to the Class Insecta. Arachnids are as distant from insects, as birds are from fish. It really is not a trivial distinction!
3.) Myth: All spiders make webs.
Fact: Technically, a web is not just anything a spider makes out of silk; it is a silk structure made to catch prey. Only about half of the known spider species catch prey by means of webs. Others actively hunt for prey (including members of the wolf spider, jumping spider, ground spider, sac spider, lynx spider, and other spider families), or sit and wait for prey to come to them (trap door spiders, crab spiders, and others).
4.) Myth: You can always tell a spider because it has eight legs.
Not exactly. Scorpions, harvestmen, ticks, and in fact all arachnids – not just spiders – have four pairs of legs. Insects have three pairs. Also, notice that I said "four pairs" instead of "eight." The number of leg pairs (one pair per leg-bearing segment) is more significant than individual legs, which can be lost.
5.) Myth: Most spiders could not bite humans because their fangs are too small.
That may actually be true of a few of the smallest spiders, and of groups like crab spiders that have small fangs. However, there are well-documented human bite cases from spiders as small as 3 millimeters long. (The bites caused no ill effects, of course!)
It’s not that spiders can’t bite, but that they don’t bite except very rarely. And on those rare occasions, the bite almost always has only trivial effects on the human, who after all weighs from one to several million times as much as the spider!
6.) Myth: Spiders are easy to identify.
No such luck! Laypersons often assume that there are only a few spider species around, and all they’d need to identify them would be a few pictures. In reality, the world holds over 50,000 species of spiders classified into over 100 families. In your local area, there are likely at least 30 families and a few hundred species.
Even identifying a spider to family is no trivial task; all the many published keys to spider families are so organized that a beginner will go wrong about half the time. At species level, one needs an expensive microscope, a library of hundreds of separate books, monographs and articles, and a few years of experience to understand the many microscopic details that identify a spider, their similarities, differences, and variation.
7.) Myth: A deadly exotic spider has been found lurking under toilet seats in airports and airplanes.
This urban legend began in August, 1999 as a deliberate Internet hoax, disguised as a news story. The original version refers to a spider allegedly called Arachnius gluteus,
or South American Blush Spider. Nothing mentioned in the story is genuine; there is no such spider, no such airport, no such medical association, no such doctor, no such restaurant, and no such aeronautics board.
In October, 2002 a new version of the same hoax surfaced. This one mentions a real species, the south Asian jumping spider Telamonia dimidiata, but it is still a hoax. A jumping spider is one of the least likely to be found in such a situation; they are sun-lovers, and none are more than mildly toxic to humans.
8.) Myth: Tarantulas are dangerous or deadly to humans.
Outside of southern Europe (where the name is used for a wolf spider, famous in medieval
superstition as the alleged cause of "tarantella" dancing), the word tarantula is most often used for the very large, furry spiders of the family Theraphosidae.
Hollywood is squarely to blame for these spiders’ toxic-to-humans reputation. Tarantulas are large, photogenic and easily handled, and therefore have been very widely used in horror and action-adventure movies. When some "venomous" creature is needed to menace James Bond or Indiana Jones, to invade a small town in enormous numbers, or to grow to gigantic size and prowl the Arizona desert for human prey, the special-effects team calls out the tarantulas!
In reality, the venom of these largest-of-all-spiders generally has very low toxicity to humans.
9.) Myth: Spiders can lay their eggs under human skin in wounds created by their bites.
In a surprisingly widespread urban legend, a nameless woman is bitten by a spider (usually on her cheek) while on vacation. She later develops a swelling, from which, in due course, baby spiders emerge! Somehow or other, the venom must have transformed into eggs. Spiders, need I say, do not find the human body a suitable site for egglaying, and no actual case anything like this can be found anywhere in scientific or medical literature.
10.) Myth: Some spiders are deadly.
Fact: There is no spider species anywhere that can properly be called "deadly." Obviously, a few people have died from spider venom, but I know of no species anywhere on earth capable of causing death in humans in as much as 10% of cases, even if untreated. If the person bitten obtains medical aid, death from genuine spider bite ("mystery bites" falsely blamed on spiders don’t count) is almost unknown in North America and a decided rarity worldwide. "Deadly" spiders that can incapacitate you in minutes? Only in the movies!