i based my design loosely on commercial feeder that i saw. as with several things that I've built for bee hives & bird houses/feeders the designs evolve over time. mealworms are a favorite for many birds including house sparrows & starlings. one year a robin dominated the open feeder & drove off rivals. these days they pretty much ignore them. the first feeder worked but this newest is a big improvement. i've seen bluebirds & carolina wrens completely inside the jar. the original feeder is in the last photo.

the lid pivots on 2 screws. a double headed nail is inserted into a drilled hole to hold it closed. the simpler the better. the entrance hole is too small for larger birds.