Question for Torchwood fans

[FloridaJudy]

Where the dickens do the Weevils get their boiler suits? They aren't obviously bright enough to have manufactured them themselves. Are they an escaped slave race that's gone feral? And why would they even bother to wear clothes? I know it saves the special effects department the expense of making a naked Weevil costume, since all they have to create is a Weevil head and Weevil hands, but it just seems peculiar.