I saw a lot of cockroaches are basically black or brown good horror this may be a long time since evolved to protect the color ! Cockroaches prefer dark, damp place to survive without the protection of this natural color will be eaten by predators , or the like are you a slipper to shoot dead, so future generations of cockroaches on a growing number of black or brown , slow they slowly become essential travel home stuff Caesar , Thank you! Leaders, distinguished audience of this report is completed ! round of applause! ! ! !