Don't Judge Me...I Know It's Gross!

This evening I came home to find this lovely sight. That's right-that would be fly larvae in a cup on my office desk. Now, I will take the blame for this cup sitting here. It is my fill-with-water-every-time-I-get-on-the-computer-go-to-cup. I don't think it's gross at all that I do that. It's like the person who reuses their coffee cup daily. So.......what? What you cannot see in the picture is the mama who laid these eggs-she's 'a floatin' in the middle-gone up to fly heaven I suppose.....Well, let me get back on topic. Anyway, I immediately looked up house flies and their gestational lifespan/how it's all done, and I came upon this site. I read all the info and I just don't see why this happened. I know flies like a warm, moist place to lay their lil' darlings. So.....moist-check! (it's a cup of water, duh!), and warm-not so much a check. Even this room she chose to procreate in is super cold. Hmmm......why does the gross bug stuff always happen to me? Dunno, I'm not a gross person. Why?! WHY?????!!!!!!!!!