“Off feed”?

[Matttoadman]

So is it a good idea If you open a food you have been feeding for years 2 out of your 3  colonies appear to not eat it that it could be contaminated? I have used the cheap $2 bad of cat food to feed my roaches once every two weeks (oats daily). This bag they have left it uneaten for two days. I think the roaches may know something I don’t 

 

[Axolotl]

How long have you had the bag of food? They might just be bored. I notice mine love certain foods for awhile (typically chow), but then won't eat it again until I break up the routine. If they don't eat it, you might as well be safe and just get a new fresh bag.