Howdy mokak
I recently experienced the same issue.
Bad timing on my part meant that I could not get to my normal Feed Store and I popped around to the local market which sells small bags of chicken feed that would have done me until I could get to my normal store.
PS. I note you called it "chook food" .. Aussie perhaps? Would be a huge coincidence if it was the same market!
Anyways, I got the bag home, it was in another plastic bag with handles, luckily looked inside the bag before I got inside the house and it was crawling with little black bugs! Little black bugs all over the back seat of the car also!
I put it back in the car and drove back to the market. Explained the situation and they offered to replace the bag; each bag they bought out had little black bugs in it! I told them not to bother, went home, fumigated the car and swore to never shop there again!
The shop assistant told me that it was not their fault as such and the bugs eggs would have come in on the grain ... I have had chickens for two years now and never had the problem before or since.
