Yes, congrats on your bluebird nest & eggs. Don’t you just love it? I’ve got a pair with 6 eggs- hatching should be coming soon, so I’m keeping my fingers crossed.
As far as dry mealworms, my bluebirds absolutely love them! I started supplying them when a pair nested in my yard last Spring & that same pair has been visiting ever since. I live in the south, so they fed on my dry mealworms all winter long. This is a great time to introduce them since you already have a pair nesting in your yard. The key is to put them in a location where the bluebirds will discover them.
Hope it works out!