Where Are the Robots?

I find it curious that in the first eight or ten years of the Flash Gordon comic strip, not a single robot makes an appearance. As far as I can tell, the first time a robot appears in any version of Flash Gordon is in the 1940 motion picture serial, Flash Gordon Conquers the Universe, which introduces the Annihilatons. I've made it to 7 September 1942 in the dailies and 4 February 1945 in the Sundays, and not a robot is to be seen. All of this causes me to wonder: Was the absence of robots in the comic strip deliberate, or was it an oversight? If the absence was deliberate, what was the reason? And who was the first artist to bring robots to the strip? I can't wait to find out...