Arthropods are usually not welcomed guests in many people's eyes. We drive them away, spray pesticide to them, and smash them with all kinds of tools out of our phobia toward arthropods. But are they really harmful to us? Our goal in this project is to find out the identities of a few species appear frequently in and around buildings using DNA barcoding. With that data, we will be able to study species concerned further, and find out their ecological positions and values. We will also find out if these arthropods are harmful to humans. We can then avoid rrepelling or killing beneficial or environmentally friendly arthropods.