No this is not beating a dead horse; it is resurrecting one still nagging some of us.
As I recall, we had a bit of fun with the Latin pronunciation thread, championing the idea of common usage to justify our pronunciation of baetis, and taking Caesar's name in vain. However, we did not come up with any consistent key to ennunciating those long polysyllables naming our exoskeletoned friends.
Recently surfing Jason's photos in an attempt to identify some nymphs, I stopped at the Family Heptageniidae and realized that the pronunciation of the double i had me flummoxed, so I did a bit of Googling. The result was the following website:
This site not only tells why the ae in baetis should always be pronounced as the a in plate, but also why we pronounce the ae in Caesar with the sound of e in beet, a seeming inconsistency. For anyone who has tended to mumble his or her bug Latin, or to cough as it was pronounced, this site will give you new confidence. It does appear that I'll have to abandon my beloved pronunciation of the feminine plural -ae as the i in time, except, or course, when reciting Catullus.