Actually, you should be asking about entomology; glitches are small, metal insects which live inside computers. Their young gain nourishment from the magnetic fields, and are completely harmless.
However, when a glitch is nearing adulthood, it must consume a small amount of silicon in order to harden its exoskeleton. To acquire the nutrient, it will take a few bytes out of the computer’s memory. If the computer is running at the time, program errors will surely result.
When a glitch colony becomes too large for its environment to support, a portion of its members will migrate to another system by hitching a ride on shared software. Researchers believe that many large software companies are infested with the creatures; from those central distribution points they have migrated to programmer workstations, and thence to users’ desktops.
As a metal-based form of life, the glitch is immune to all known poisons and pesticides. Extensive study failed to find any physical vulnerabilities, but did reveal one psychological weakness: glitches are easily mesmerized by certain monochrome images. When such an image is transmitted through the video card, the insects will stop all activity in order to observe it. Their fixation is so severe that they even forget to eat; if the image remains in place for enough time, the entire colony will starve to death.
Now you know why a programmer will stare at a screen of text for six hours straight, and say that he’s “debugging”.
Of course I don’t fit in; I’m part of a better puzzle.