Specific questions about keeping dubias and not a breeding colony

[Sandhouse]

I can't keep a colony but I won't bore you with the details of that. I want to keep 50-100 small (up to a half inch) dubias at a time. I'll order them online.
Do most geckos transition well from crickets to dubias?
My room is 65-70F and they would be in my walk in closet. Do they need heat and if so can I slap a small UTH on it and call it done? I don't have a thermometer right now.
Can they stay in shoebox sized plastic containers or my large cricket keeper? I have several plastic storage boxes hanging around and it would be convenient. I actually have two lids with holes already but when I used them for mealworms (which they won't eat at all) the substrate ended up with mold and there was a ton of condensation on the sides. My understanding is that dubias need no substrate and do need moisture so would this be ok? Maybe drill more holes? I live in Georgia (USA) and mold loves it here. Would keeping food changed out be enough to keep out mold and all that?
Is there one or two cheap staple foods I can give them? I just use baby carrots and oatmeal for the crickets. What if I just added banana slices or something? Would that be too mold prone?
Do they die easily if I do anything slightly wrong? My crickets love to die. I'm hoping for something as tough and easy as mealworms.
Some info on my geckos: I have a baby leopard gecko, a half grown fat tail, and a crested that eats a cricket or two once a week (which he doesn't have to have obviously). They're big cricket people.

 

[indyana]

Most of my geckos have taken to dubia right away or with a bit of coaxing (as in feeding only dubia for a while until they are hungry enough to try them).

You can keep them in anything with a bit of ventilation that doesn't have holes to escape from. They can't climb smooth walls, although the adult males can jump/flutter a bit. I wouldn't provide heat unless you room gets cold; it will help slow down their growth and keep them small. Keep in mind that these will grow too large for some geckos, and geckos will eat fewer dubia than crickets. I'd start with a smaller batch so you can judge how many you need at a time. Getting 50-100 sounds like way too many for three geckos. They will grow to adults and start breeding way before your geckos eat them all. If you don't want a colony, you'll have to pick out the big roaches and pop them in the freezer so they won't breed.

Dubia frass will build up on the floor, but keeping it dry will help prevent mold. For moisture, you can provide vegetables like hard squash and carrots and/or water crystals/gel. Changing those out regularly (every 2 days or so) will help keep mold down. Egg crates are usually used to give them a place to hide that can be easily replaced when dirty.

For food, I'd invest in a bag of bug chow (or make your own) to give them a complete diet. What goes into your bugs goes into your reptiles, so you don't want to cheap out, especially if you're going to be feeding directly from the bin.
Some decent brands, although there are others:
Repashy Bug Burger (can get many places online)
Pro Gutload Food & Water :: Insect Food
Pair the chow with a moisture source as above. Stick to things that are good gutloads (bananas are not, for example). Here's a good outline of vegetables good for reptiles:
http://bluetongueskinks.net/foodchart.html
The Anatomy of Gut-Loading | Ingredients & Nutritional Info | Much Ado About Chameleons

Once you get a good box set up, dubia are very easy to keep and very hardy.