a brief history of the D&D water termite
A few months ago, a poster in the Something Awful OSR thread asked about the origins of water termites.
I didn't remember the monster at all, but it's written up in the Mentzer BECMI Expert set, across from an illustration I remember quite well:
(Not a standard Tyrannosaurus, but still scary.)
But it turns out the large little aquatic roaches originated in the Moldvay B/X Expert set:
I didn't have any luck chasing things down further than that. Water termites fall into the adversarial-DM category of monsters (rust monsters, yellow mold, kender), so they might be any of the old TSR designers' work. My guess was Steve Marsh, but only because he made up a lot of the other classic scary sea creatures.