- I am very familiar with redback spiders and realise they can vary widely in distribution and colour eg black with red-stripe in Sydney or brown with more orangey-red stripe in the kimberley region. Its just that I have a number of red-back shaped spiders in my worm farm that totally lack any stripe. They are just black. Is this a population of black widows from the USA? There are at least 5 adult females present with numerous white eggsac balls, and of course lots of little males also present, but the females totally lack any stripe or colouring other than black.I've been studying them for a couple of months now to see if any colour appears, but nothing so far. Is anyone able to tell me if this is a sub-species of red-back or something different?