Thank you Holly for sharing your photo! If anyone else would like to share a photograph of nature send it to firstname.lastname@example.org with a description and permission to post it on the Friday Photo.
It's not necessary to feed birds but as you can see it's fun to watch nature up close, and you'll be amused at how quickly a relationship develops between you and the bluebirds!
Bluebirds are primarily insect eaters in the spring and summer. The rule of thumb is to offer about 15 mealworms per bluebird once or twice a day, as a supplemental food, unless severe weather conditions limit natural sources. 100 or so worms offered morning and evening would be adequate for a pair with a box of nestlings a week old.