It's true. We went to the park at 7pm and didn't see or catch anything. Went to the same exact spot in the park at 9:30pm (30 mins after dark) and saw at least 5 or 6 large mantids right off the bat. Only caught 2 grasshoppers but that may be partly due to my flashlight batteries going dead. I heard lots of katydids in the trees... might try a combo of bush beating and sweep netting tonight to see if I can knock em out of the trees!