Update. I boiled and ovened the lid again yesterday after finding that one bug. Today I see 2 of them. I wonder if they are breeding/hatching from inside the middle of the lid and crawling out from the little damaged bit at the side. Also wondering if the middle of the wood is maybe damp even though I have ovened it 150c at 1 hour. I thought heat was suppose to kill potential bugs? I have taken the lid out to monitor it I case it came from my hammy, but if that was the case, they would of appeared everywhere else but there's nothing. Just that lid. Might just need to get a new dig box as am worried the wood used to make the lid and dig box is maybe habouring undestroyable beasties
