What Makes A Redback

I really do apologise for the quality of photo here. Dratted phone. So I added the old photo of the mummy redback just to try to give a clear photo (that photo is a good 18months old or so) However, the little lady in the top photo fell off one of the bins I was lifting. I always get that 'hmmmmm, thats not a good thing is it?' vibe when this happens. I think she had made her web right where the handle for the bin was, so it could have ended quite badly if she hadnt fallen. For those of you wondering, how I know thats a female Redback Spider, well, only the females look like this. She wasnt particularly big, possibly as big as the nail on my pinky finger. I have seen them get an abdomen thats a good 2cm across. But only the females are the entirely black with the red stripe down their abdomen. The males are always much smaller, less then half the size of a female, and have a browney black body, white abdomen with a browney black stripe. The juvenile females are more browney black, their abdomen is a mix of whites, blacks and brown with the beginings of the red stripe. So if you see a funny looking Redback, whos abdomen isnt the characteristic black, chances are youve come across a juvie.