Nola graciously gave permission to reprint the plans. Chickadees don't seem to mind freshly frozen mealworms, but other birds might. Bob Anderson, Olmsted Co., devised a heat tape wrap around the tuna can holding the mealworms. Others have devised a low-wattage light bulb underneath a cutout in the floor. When those early spring bluebirds arrive and insects are not abundant, the availability of mealworms in the vicinity of your bluebird nestboxes may be the difference between attracting bluebirds back to your yard or having them move to a different area to begin their nesting activities.
Mealworms are easy to raise.
Only a few basics need be followed to start and maintain a mealworm colony for a constant supply. In addition to bluebirds, mealworms will attract a wide variety of popular bird feeder visitors. The Midwest birds listed below LOVE mealworms and may even have a preference for them over and above black sunflower seed. In other geographical areas an even greater variety of birds will be attracted to mealworms. I get mine from Rainbow Mealworms P.O. Box 4907,126 E. Spruce St., Compton, CA 90220.