When I was tying commercially, there were a few terrestrial patterns I sold quite often & they were always present in my own fly boxes. One was a similar ant pattern to what moucheur2003 mentioned, but a hard bodied version made with 2 lumps of either black or red acetate floss, and about 2 turns of hackle. The hackle could be black, red brown, bright red or a dark red, either rooster or hen. Acetate floss when dipped in acetone hardens. It's not the best procedure due to the fumes, but does make a good fly. Another was made with thread lumps & epoxy coated. The most purchased sizes were 12, 14 & 16.
There were 2 beetle patterns I sold most. One was made with a shell of foam, and micro cactus chenille under the foam. The other beetle was spun deerhair, tied on a nymph/wet fly type hook to get a bit more weight & clipped to shape. Black was the most common color, but I did them in other colors as well. However sizes varied more, from 16 up to 8, as they made great panfish patterns too!
Another pattern that I sold a lot was a deerhair worm. Tied on longer shank hooks, usually nymph/wet fly types, which was nothing more than deer hair tied in at the rear of the hook, twisted some & laid along the hook shank over a thread base. The tying thread was left at the rear of the hook & the body was ribbed with the thread. Then the deer hair was tied down behind the hook eye & the extra hair was clipped to form a bit of a head. Very simple & easy to tie, but worked quite well. I made foam versions too, but they didn't have the same appearance as deerhair. Green (bright green/chartreuse) & natural tan deerhair was the most popular colors, and 12 & 14 the most popular sizes.