If you went back to that same spot, what you saw are probably Solenopsis xyloni and not Dorymyrmex bicolor. I haven't seen any D. bicolor there at all compared to at Chino Hills State Park, where they're everywhere along Carbon Canyon Road. There's plenty of Forelius sp. and D. insanus activity in that spot though. I checked it out on Wednesday and couldn't find the Myrmecocystus either, but I didn't search that hard.
That's possible. All I know is they were about D. insanus size and made similar little mounds.
