Are Spiders Insects or Bugs? The Simple Answer

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Are Spiders Insects or Bugs?

The odds are overwhelming you have heard someone casually refer to a spider as an insect. You’ve probably heard someone talking about their house having, “Bugs,” in it and then they’ve said, “You know, like flies, spiders, ants, that kind of stuff.” Well, spiders are actually not insects or bugs–they are arachnids! Should you be curious just what exactly an arachnid is and how it differs from (and compares to) insects read on, but first let’s tackle the biggest question you’re likely to hear upon hearing a spider is not a bug.

Aren’t Bugs Anything Like Spiders, Flies, Ants, Wasps, Bees, and so Forth?

The word, “Bug,” is the kind that is overused so often it is basically colloquially said as a catch-all for anything from flies to ants to spiders and bees. It is kind of like how sometimes people will call any tissue they see a, “Kleenex,” even though that is just one brand of tissue in the whole world–it has become casually accepted as the word to use even though when one thinks of tissues a wide-range exist from Scotties to Puffs. Keeping that comparison in mind, spiders and insects are both invertebrates (just like how Kleenex and Puffs are both tissues) but very different, “Brands,” of invertebrates if we may run this metaphor into the ground! Should you want to get even more technical, not even all insects count as, “Bugs,” with the formal term of bugs being certain insects that belong to the order Hemiptera (these include aphids, cicadas, leafhoppers, planthoppers, and so forth). As only insects can be bugs spiders are not either; spiders are (as was previously mentioned) arachnids. What is an arachnid, however?

What Makes Arachnids Different From Insects

There is an old song children sometimes learn in schools that contains some lyrics that actually point-out some of the key features of why spiders are not insects. For a bit of fun let’s note a lyric down and then elaborate on how it discusses the way spiders differ from insects until we’ve discussed all the key lyrics.

“Spider Bodies Are Two-Part. Spider Webs Are Works of Art”

Insects have a head, thorax, and abdomen. From the thorax there are six legs total. Spiders however, only have two main parts to their body just as the song indicates. Spiders have a cephalothorax and abdomen, they basically lack a neck. The celphalothorax contains their eyes, mouth, and eight legs. The whole body of the cephalothorax and abdomen is covered by a strong exoskeleton and there are generally sensory hairs that grow-out from the spiders body. Other animals that are like this are in fact mites, ticks, and scorpions, with all of these falling into the group known as Arachnida, and spiders being in a specific group called Aracnae. Hence, spiders, ticks, and scorpions all are arachnids but only spiders are aracnae. Now, not all Arachnids can weave webs or spin silk, but any animal that is a part of Aracnae have spinnerets and can spin silk even if they do not actually weave full-on webs for their hunting of prey.

“Spiders Seldom See Too Well, Spiders Have No Sense of Smell”

Spiders eyes are actually not that powerful when compared to insects which have a, “Complex,” set of eyes. Spiders have four pairs of eyes–e.g. eight total. Also, insects are known to, “Smell,” with their antenna whereas spiders do not have any. Therefore, spiders literally have no sense of smell. Whereas insects need this sense of smell to pick-up pheromones and communicate with one another, a spider’s solitary nature except for when mating results in such a sense therefore being of little use, so spiders lack it. One may be wondering how exactly spiders navigate around the world if their eyesight is relatively poor and they lack a sense of smell. The answer is that spiders heavily utilize their senses of touch, ability to, “Feel,” vibrations, and stimuli such as taste when they are navigating and looking for prey. A good deal of spiders can sense light-versus-dark and use that to help them with being aware when to spin a web (if they make webs) or to go wander around for their hunting. Spiders also have a great deal of neurons in their body which results in a very complex neurological system that assists with quick movement and processing of the environment so as to assist with hunting or avoiding things that might try to eat/smash the spider. They do not always, “See,” well with their eyes by any means, but they, “See,” extremely well with their other senses working together, so-to-speak.

“Spiders Don’t Have Any Wings, Spiders Live on Living Things”

Almost all insects have wings with only fleas, silverfish, firebats, and lice lacking them. Even insects which do not generally fly often have wings that are mostly non-visible or nonfunctional (ants and temites, for example). Insects known for their wings and flying about include everything from butterflies, to moths, beetles to cockroaches, and that infamous pest, the housefly. Also, while half of insects in existence survive by eating plants and others eat smaller insects or even drink blood (mosquitoes), spiders only ever eat other animals to survive (e.g. it lives on, “Living things,” as the song goes). It is also notable how insects can have various methods of eating (sometimes mandibles for chewing, other times they, “Sponge,” with a proboscis, and even more means) a spider only eats via their chelicerae. A chelicerae is sometimes more commonly called, “Fangs,” or, “Jaws,” and they are hollow along with having venomous glands. This allows spiders to chomp-down on their prey and inject the venom which liquefies their meals insides and allows the spider to suck it up as if thick milkshake through a straw (with the straw being the hollow chelicerae). Do be aware basically all spiders have venom, it is just that only species are poisonous to humans, hence some spider bites sting a bit but are otherwise unremarkable and some spider bites can kill even a human adult!

“Spiders Always Have Eight Legs, Spiders Hatch Straight Out of Eggs”

As has been touched-on above, spiders and all other arachnids have eight legs. It also bears mentioning that insects (as with their differing eating habits) can at times all reproduce in quite a range of ways. Some insects lay eggs which then hatch into a larva, then becomes a pupa, and then is an adult insect. These stages are often known as being a part of the process known as Metamorphosis and can be observed in a wide range of insects such as butterflies (which start-out as caterpillars) or bees which are known for how they make honey to help feed their developing young. Not all insects lay eggs that go through these stages, though. Some insects such as aphids engage in what is known as, “Viviparity,” which is where they birth live young who then grow over time. Insects are quite complicated clearly, but when it comes to spiders they lay eggs, the eggs hatch, and a spider is born which then grows over time. That’s it, not wild or crazy stages, just a spider growing! Now, while spiders do molt (as process that involves shedding their exoskeleton for a larger one to assist with continued growth) that is by no means as in-depth of complex a process as Metamorphosis. Spiders lay eggs and hatch out of them, its as simple as that (do be aware insects molt too, this will be discussed shortly). Want to know more about how spiders hatch out of eggs? Take a look at our article How Many Spiderlings Can a Spider Have?

“Since All These Facts Are Surely So, Spiders Are Not Insects, No!”

As these facts the song discusses all make abundantly clear, spiders are very different from insects in a number of ways. However, it was mentioned they are both invertebrates and it is worth discussing how arachnids and insects are similar in some ways.

Shared Aspects of Arachnids and Insects

While spiders and other arachnids are a whole different kind of animal than insects, they do have certain shared features. Three big ones bear pointing-out.

Both arachnids (such as spiders) and insects have a hard skeleton, the earlier-discussed exoskeleton. This means that arachnids and insects actually do both molt. Even insects that earlier in life have their complex metamorphosis will then later-on in life once adults engage in molting as they continue to grow and need a larger exoskeleton. Speaking of molting… ever wondered if spiders’ fangs grow back after they molt? Find out in Can Spider Fangs Grow Back?
Spiders have segmented bodies and insects do too. Even though spiders may have two segments and insects have three, the fact they are segmented is a key shared trait.
All arachnids and all insects have jointed legs. Having a jointed leg literally means at some point along the leg it is designed to flex (humans have a jointed leg, for example, as we have a knee). One big advantage of having these jointed legs is it assists with having more flexibility and a wider-range of motion. Considering how arachnids and insects often need to be able to move quickly and find their way through tight spaces (such as in a house or a leafy forest) a jointed leg is clearly a great feature to have!

Why Do People Incorrectly Call Spiders Bugs or Insects?

By Harald Hoyer from Schwerin, Germany - Baby Spider, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=24326119

There is no exact reason why spiders are often incorrectly identified as insects. People are not doing it maliciously, as if they want to insult a spider by saying it is an insect as opposed to an arachnid, it is arguably just ignorance and indifference. It is kind of like how Gorillas and Chimpanzees are not in fact monkeys, they are apes, a whole different species. However, lots of people will probably see one at the zoo and say, “Look at that monkey!” regardless of if they are inaccurate. In the same manner, a parent who does not know much about video-games beyond playing a Super Nintendo when they were young may yell upstairs to their child, “Turn off your Nintendo, its dinnertime!” even if their teenager is playing a PlayStation 4 or Xbox One.

Basically, a mixture of ignorance and indifference makes us call something that is, “Close enough,” in our minds. After all, if you tell someone, “Actually that’s an ape and not a monkey,” they will probably say, “They are a lot alike though,” and in the same manner arachnids such as spiders are a good deal like insects as was just discussed it makes sense people might confuse the two–or to return to that earlier metaphor, someone calling a tissue a, “Kleenex,” regardless of its actual brand will probably say, “Well, I wanted a tissue, so you know what I meant.” Hence, if someone calls any invertebrate animal a bug or insect whether it is an ant, bee, spider, scorpion, or butterfly, correcting them might get you a curt, “You know what I meant.” This is not to say you should be shy of telling people about how spiders are in fact arachnids, just be polite when you point-out to people they are incorrect or try to only discuss it with those who you know will not take offense at being corrected–we as human beings rarely like being told, “You’e wrong,” about anything, so do work to spread the knowledge of how spiders are not insects, but do it with a good attitude and friendly demeanor–e.g. say, “You know, spiders are actually arachnids and I’d love to tell you some neat facts about why,” instead of, “Wow, you’re dumb, spiders are not insects, moron!” Basically, tell others the truth about spiders but don’t be a jerk and you’ll be fine.

In Conclusion…

As this article has laid-out, spiders are not insects or bugs, they are arachnids. After reading this piece you now are well-versed in all the ways arachnids are different from insects and how they do have some similarities too. You’ve also been given some advice on how to politely tell others all the fascinating things about spiders you have learned via this article the next time a person incorrectly calls them an insect. Spiders are clearly many incredible things, but one thing they surely are not is a bug!

If you enjoyed reading this article, why not check out our articles on How Do Insects Hear? The Curious Answer and The Three Best Kinds of Spiders to Keep as Pets