Have you tried just baiting them into a perforated bucket?
What you do is lower a "jummy" last meal into a small perforated bucket (drill some holes with a drill) and wait 30 minutes for the bucket to fill. Then you remove the bucket from the bigger colony and you feed those to your chickens...
I have 2 papers on how to optimize productions and yes harvest is very crucial. I'm not sure how effective the DIY tubes are.
http://learn.compostmania.com/hawaii-workshop
Robert
Post a picture if you can
yes smell is your number one tool when assessing overall health.
I've noticed that once the number of grubs get to a certain level it can still take a few weeks for the bacteria to get optimized. Once that happens it's like a next wave of bio-productivity. Typically...
Honestly,
I would never feed grubs from a stinking food source. The smell you are smelling is there for a reason and indicates anaerobic bacteria. You probably have moisture accumulating in your unit. When people let chickens go into their compost pile you have to assume that the compost is...