- All bugs are insects, but not all insects are bugs. Even some of the insects that have "bug" in their names are not true bugs. The lightning bug, the ladybug, the June bug, and the potato bug are not bugs. They are beetles.
- True bugs (Hemiptera) have transparent outer wings that overlap a little at the tip. Their legs are long and slim. They have mouth parts with which they can pierce a plant or an animal and suck out the juices.
- Hemiptera includes around 50,000–80,000 species of aphids, cicadas, leafhoppers, planthoppers, shield bugs, and others.
- Some bugs have names that fit them very well. The squash bug sucks the juice from squash plants. The assassin bug kills many other insects. The ambush bug lies in ambush among leaves and flowers and watches for insects it can catch. The toad bug looks as warty as a toad and goes hopping about in search of food.
- True bugs range in size from 1 millimetre to around 15 centimetres, and share a common arrangement of sucking mouthparts.
- Most bugs do little or no harm. A few do some good. The assassin bug, for example, eats many grasshoppers and potato beetles. But some are our enemies. The chinch bug, for instance, does a great deal of damage to our crops.
- The fossil record of hemipteran bugs goes back to the Early Permian.
- A few true bugs are parasites, feeding on the blood of larger animals. These include bedbugs and the kissing bugs.
- Aphid bugs are born pregnant and can give birth when they are only 10 days old.