|MadSci Network: Zoology|
Well the note that comes from the honey bee is caused by the rapid beating of it's wings. Honey bees are the species Apis mellifera and grow to a size that is average for that species. So similar sized wings give you similar note. Each bee sounds like her sister! A different "note" would indicate an intruder at the nest or a predatory wasp or robber fly nearby in the trees. If you want to know more check out Why Bees Hum at
And lots more on bees at http://www.main.org/cahbs/biology.htm
Admin note (added by Rob Campbell)
The sound that bees make is indeed related to the frequency that they beat their wings at. That frequency does vary a bit (e.g. see this search) and it probably depends on the species, temperature, and a lot of other things. If a swarm of bees is fairly similar (from the same species, hive, etc), then they might make a pretty similar noise. There's bound to be some variation, but would be less noticible in a swarm.
Try the links in the MadSci Library for more information on Zoology.