Moths - bearer of ill omens

I am not a superstitious person but for some reasons or coincidences, I've come across many stories about moths and how their appearances often coincide with bad things. For example, ever since I was a small boy, my mum had related to me about how moths appeared when my grandparents passed on. The same happened almost yearly during their death anniversary. I heard the same story from my aunts... and the storyline was quite similar. And this week, a close friends' dad passed on. When I visited the wake, the family members told me how they felt uneasy when a moth appeared in their house and refused to leave. Instead, the moth flew around and found its place at the family altar. That very night, the dad passed on...

Coincidence?