Beetle blades appear in a number of chapters. They are small, metal creatures that spy on the Gladers. The Gladers believe that the beetle blades alert the Grievers to their location. They look like silver metallic lizards; however, they have twelve jointed legs. There is also a red beam of light that shines from their heads.

Thomas is able to get a really good look at the beetle blades in chapter 18. He's forced to climb up the vines and hope they provide enough security for himself and Alby. He gets himself and Alby about 30 feet off of the ground, but he is too exhausted to go any higher. The Grievers are closing in on his location, and Thomas realizes that there is a beetle blade within a few inches of his face. This gives him a clear look at the torso, and Thomas is able to confirm that the word WICKED is written on the beetle blade.