I have kept crawlers for most of 50 years. At home (and I've moved a few times) you will find a big box of some kind (screen lined wood or modified old chest freezer....something) of big box near buried in the shade. It is filled with soil, Sandy Loam, peat, commercial bedding, clumps/roots of grass and shredded newspaper on top. Fed worm food, cornmeal/powdered milk, coffee grounds (usually a mix of last three). I HATE Styrofoam cups from a refrigerator transported in a cooler or not and Styrofoam coolers for transporting and on the water don't suit me. Perhaps on 90 degree days and 70 degree nights it is better; but I don't fish much when it's that hot. (Maybe during a Summer Cool Spell) Mostly after August and before July. Have used all the Styrofoam bait boxes and the double end kidded one's too for a dozen or two and big foams for more.
I personally like the wettable particle board crawler boxes...Bait Canteens or whatever the plastic framed/handled one's are called now. Have kept 7 dozen (at start) for a weeks trip. In weeks of 45-55* nights and 60-80* days - I like the evaporative cool the best.
The change from a styro cooler(often with an ice pak) to warm water seems to take much life from a crawler soon after it hits the water.
Kept crawlers and used "Bait Canteens for many years and still learned some nice tips from the book "Lunkers Love NightCrawlers". If you like Crawlers this book is a good read for Keeping and Conditioning worms and Fishing them.
Anybody else babysit crawlers for that solid lively healthy squirming Presentation?

Hey OTH, you ever tasted the worm food taste like oatmeal to me. Thats what I feed my crawlers. Just mix it up and apply to the top of the worm bedding with a syringe. If you feed too much it can mold and can kill the crawlers.

Never tried it. Thin paste? Mix with water? Thanks.

I personally keep my crawlers in a "bait canteen" as you mentioned. I use regular worm bedding and a bit of black soil. I actually add a little water now and again. Not too much or often, but I have found that the liveliness of the crawlers is rather noticeable.

See