Bug vs Insect: What’s the Difference Between Insects and Bugs?

Summary:

Bug vs insect – wondering about the differences? In this guide, we walk through the differences between insects and bugs in detail, so read on to find out!

Have you ever wondered about the difference between bugs and insects?

I don’t blame you, especially with all this extra time you have to think while the world is stuck indoors.

So, what is the difference between a bug vs insect? And what are spiders and arachnids? What about creepy-crawlies such as centipedes and millipedes?

Well, you’ve come to the right place!

Let’s first outline each one separately, beginning with insects.

bug vs insect bee flying over yellow flowers
A bee is an insect, but not a bug. Taken by Trollinho via unsplash.com. [Public Domain].

Insects

Scientifically speaking, an insect is any member of the taxonomic class Insecta, under the subphylum Hexapoda. As you can guess from the name Hexapoda, all insects have 6 legs, which is one of their most distinguishing characteristics.

Aside from insects having six legs, there are other ways to tell whether a certain little creature is an insect or not.

An insect’s body is divided into three parts: the head, the thorax, and the abdomen. All insects have compound eyes, consisting of thousands of ommatidia, which are clusters of photoreceptor cells, making the close-up view of an insect’s eyes look like a soccer ball (just with way more hexagons and pentagons).

All insects also have one pair of antennae, as well as an exoskeleton made of chitin (which is the same as those on crustaceans, such as shrimp). This chitinous exoskeleton is pretty inflexible, meaning it can’t grow as the insect grows. This means insects must molt, which is when it sheds some of its external body parts giving it room to increase in size, and then a larger exoskeleton forms soon after.

However, in English, the word insect has multiple meanings, even if you don’t consider the colloquial usage to be just about any little living thing. Many scientists consider insects to be slightly narrower in scope (called Ectognatha), consisting of only Pterygota (winged insects), Zygentoma (silverfish), and Archaeognatha (jumping bristletails). With this definition, the other three groups are all Entognatha, which include Collembola (springtails), Protura (coneheads), and Diplura (two-pronged bristletails). One thing that this narrower definition of insects include is an external mouthpiece.

Did You Know? There are more than a million known species of insects already, making up more than 50% of all living organisms. And, scientists believe that there are many more to be discovered, and that insects could account for more than 90% (!!!) of all animal life forms on Earth!

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Bugs

So now, what are bugs?

Like insects, bugs are often used colloquially in English to refer to all creepy-crawlies, as well as sicknesses, computer viruses, annoying behavior, and other problems.

However, there are “true bugs,” and they exist in the scientific taxonomic order Hemiptera.

Let me digress for a moment, if you will. In biology, there are different ways to classify and group species (called taxonomy). Though there are several different taxonomic classification systems, most look something like this, from highest level on down: Life > Realm > Kingdom > Phylum > Class > Order > Family > Genus > Species. There are other groupings, as well as sub-groupings (e.g., suborder), but this is generally how it goes.

Okay, let’s get back on track. So, Hemiptera (true bugs) is a scientific order. However, Insecta (insects) is a scientific class. As you can see, they are at different levels, and actually, Hemiptera is an order under class Insecta.

This means that all bugs are insects, but not all insects are bugs.

This also means that all bugs have the same defining characteristics as all insects, including the three-part body, the pair of antennae, the chitinous exoskeleton, and the 6 legs. However, since they’re a narrower grouping, they have some specific traits that make them different from other insects.

Bugs have a stylet, which is an external mouthpiece shaped like a straw made for what straws do best, sucking. Some bugs use their stylet to reach in there and suck nectar or sap from plants, while others suck blood from larger animals. The thin, needle-like shape allows bugs to pierce the skin to get to what they want pretty effectively.

Bugs also have wings, sometimes two sets, forewings and hindwings. The forewings on bugs are usually membranous in nature and appearing translucent, while some bugs have wings that are hardened and darker as it gets closer to where it connects to the body. Actually, the name Hemiptera means “half wing,” and they got its name from those bugs with the partially-hardened wing, as it looks like half the wing is solid, while the other half, nearer the tips, is transparent.

Bugs include cicadas, moss bugs, aphids, shield bugs, water bugs, scale insects, whiteflies, assassin bugs, and sweet potato bugs. A lot of the “hoppers,” such as treehoppers, froghoppers, planthoppers, and leafhoppers, are all bugs, as well; interestingly, however, the grasshopper is not a bug, as it belongs to the taxonomic order Orthoptera rather than Hemiptera.

Did You Know? There are many little critters with everyday names such as the ladybug, the May bug, and the lovebug (not the 70’s hippie kind) that aren’t actually bugs. These belong to other taxonomic orders under Insecta. The ladybug is actually a beetle, while the lovebug is a type of fly.

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Summing Up: Bug vs Insect

So, let’s conclude!

What’s the difference between insects and bugs?

An insect, scientifically, is any creature under the taxonomic class Insecta. Insects have six legs, a body divided into three parts (head, thorax, and abdomen), a pair of antennae, compound eyes, and an exoskeleton made of chitin.

A bug is any creature under the taxonomic order Hemiptera, which is a classification level under the taxonomic class Insecta. This means that every bug is an insect, but not every insect is a bug. As follows, bugs have all the standard characteristics of an insect, including the 6 legs, compound eyes, chitinous exoskeleton, antennae, and three-part body. Bugs also have a stylet, a straw-like mouthpiece used to reach deep into places to get at their food, and bugs have wings, often 2 pairs.

Did You Know? If you’re wondering about squiggly-wigglies and creepy-crawlies such as spiders, scorpions, ticks, and mites, these are all arachnids, not insects or bugs. Centipedes and millipedes, with their dozens of legs, also aren’t bugs or insects, but rather belong to the taxonomic classes Chilopoda and Diplopoda, respectively.

Well, that’s our guide on bugs vs insects, and we hope it’s helped to clear up the differences between them for you! Got any questions, feedback, or other information to add to our writeup on the difference between bugs and insects? Let us know in the comments below, and thanks for reading!

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Christian Eilers
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Christian Eilers
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