It all depends on your attitude, size, species rarely matters. Recently I was watching a live feed on nat geo/discovery. A group of humming birds was eating honey cubes left by some charitable bird lover, a praying mantis was sitting there looking for creepy crawlies, one of the humming birds attacked it, it took a retreat and then when the humming birds forgot that it was still there it look a plunge at the nearest one and ripped off few feathers! Who said birds eat insects? you?