Can anyone ID this bug

Hi, I found a swam of these in the backyard, it's autumn in Canada, temperature is cooling (12C day, 5C night) and I have never seen these before. When I crushed a few of them, they all had red blood in them, probably from feeding on something.

Hope I can post this picture correctly:

https://drive.google.com/open?id=0B3CDW2oVIduRSEFneno2bURXdE0

Thanks!