What bug is an arthropod?

Pretty much all bugs are arthropods, with the exception of an informal usage of the Word "bug" to describe a pathogen causing an illness. All insects are arthropods; non-insect arthropods like myriapods (centipedes and millipedes for example) are called bugs and are still arthropods. Arachnids including Spiders and scorpions, which might be called bugs, are also arthropods; land crabs which might be referred to as "bugs" are arthropods.

In Biology there is a group of insects called the "true bugs", including the shield bugs; also arthropods.