There Was A Bug In My LCD Monitor!

I recently had a bug on my LCD monitor. A very small one but on the other side from me. I can touch where it is and see it moving. I searched on the web and sure enough, there are others who had similar experience. So I learned that it is better not to squash the bug. Because if I did, I will get a spot on my screen. So I let it alone and hoped it will go on its own. Fortunately, it disappeared next day. I wonder how it got inside in the first place? I was planning to keep a bright light near the edge of the screen to lure the bug towards an edge but I didn't have to try that.