I went to college for biology, so I don’t really like to use the word bug to describe something. It is just too vague a word for it to really mean much. But it is commonly used, so I shall do my best to define for you what a bug exactly is. Bugs are arthropods. Arthropods have exoskeletons, which means their skeletal structure is on the outside of their bodies. In the phylum Arthropoda, you will find insects, arachnids, myriapods (centipedes and millipedes), and crustaceans. Only a few land-dwelling crustaceans are commonly referred to as bugs—mainly the pill bug and sow bug. Even though crabs and lobsters are not normally referred to as bugs, they do meet the criteria to be a bug, however vague the definition may be. For more information on getting rid of bugs read the full article How to Get Rid of Bugs.