Difference Between Bugs and Insects

Difference Between Bugs and Insects
Bugs are one type of insects. Bugs have sucking mouthparts and partially-hardened wings and they undergo incomplete metamorphosis.

Many people refer to any crawling creature with several legs as a “bug.” Even entomologists (scientists who study insects) often group insects, bugs, and spiders together as “bugs” when speaking to the general public. But, there are differences between bugs and other insects. Here’s what you need to know.

A bug is a type of insect. All bugs are insects, but not all insects are bugs.

How to Identify a Bug (Bug Characteristics)

The defining characteristic of a bug is its “beak” or mouthpart, which forms a piercing and sucking “straw” or “stylet.” A bug folds the stylet under its body when it’s not in use.

The life cycle of a bug differs from that of other insects, too. Bugs hatch from eggs into nymphs, which generally resemble their parents. Even though young bugs molt several times before becoming adults, they don’t undergo a true metamorphosis.

However, there are other properties shared by most bugs.

  • Sucking mouthparts
  • Do not undergo metamorphosis
  • Partially hardened or fully membranous forewings, which fold over one another (although a few bugs lack wings altogether)
  • Many produce sound to communicate.

Bugs share characteristics with other insects. While these traits won’t help you tell whether a creature is or is not a bug, you can use them to rule out other animals:

  • Six segmented legs
  • Two antennae
  • Compound eyes
  • Three body segments
  • Chitin exoskeleton

Use a magnifying glass to identify a bug. Examine its wings and mouthparts. If possible, observe its life cycle.

Examples of Bugs

Scientists know about over 45,000 true bugs. Here are some examples of bugs:

  • Aphids
  • Assassin bugs (including kissing bugs)
  • Beg bugs
  • Boxelder bugs
  • Cicadas
  • Firebugs
  • Froghoppers
  • Leafhoppers
  • Mealybugs
  • Scale bugs
  • Shield bugs
  • Stink bugs
  • Treehoppers
  • Water bugs (including water boatmen, water scorpions, and backswimmers)
  • Whiteflies (despite having the word “fly” in their name)

Insects (and Other Creatures) That Are Not Bugs

Some creatures have the word “bug” in their common name, yet aren’t actually bugs. Other animals aren’t bugs, or even insects. Here is a list of animals that are not bugs:

  • Beetles (insects, but not bugs)
  • Lady bugs (which are beetles)
  • Bees (insects, but not bugs)
  • Butterflies and moths (insects, but not bugs)
  • Cockroaches (insects, but not bugs)
  • Flies (insects, but not bugs)
  • Locusts and other grasshoppers (insects, but not bugs)
  • Pill bugs or woodlice (arthropods, but not insects)
  • Mantises (insects, but not bugs)
  • Spiders (arthropods, but arachnids and not insects)
  • Mites (arthropods, but arachnids and not insects)
  • Ticks (arthropods, but arachnids and not insects)
  • Centipedes (arthropods, but not insects)
  • Millipedes (arthropods, but not insects)
  • Lobsters and crabs (arthropods, but not insects)


  • Cassis, Gerasimos (2019). “True Bugs (Insecta: Hemiptera: Heteroptera): Evolution, Classification, Biodiversity and Biology”. Reference Module in Life Sciences. doi:10.1016/B978-0-12-809633-8.20710-3
  • Chinery, Michael (1993). Insects of Britain and Northern Europe (3rd ed.). Collins. ISBN 978-0-00-219918-6.
  • Ruppert, Edward E.; Fox, Richard, S.; Barnes, Robert D. (2004). Invertebrate Zoology (7th ed.). Cengage Learning. ISBN 978-81-315-0104-7.
  • Wheeler, Alfred George (2001). Biology of the Plant Bugs (Hemiptera: Miridae): Pests, Predators, Opportunists. Cornell University Press. ISBN 978-0-8014-3827-1.