Doodlebug is the nickname given to the larvae of the Antlion Lacewing (
wiki link). So named for the doodle drawing designs they create in the sandy soil. They build sand traps to catch their prey (photo below). The insect, once in the trap, cannot escape due to the steep walls of loose soil.
There are several of these traps along the edge of one of my barns. Today I noticed that a nearby hatch of harlequin bugs were getting caught in the traps and being killed by the doodlebugs. Last year I had planted lots of turnips near the barn and they attracted loads of harlequin bugs. Now that this years harlequin bugs are hatching they will find no turnips (crimson clover now there) and they'll find an increased number of doodlebug traps.
I took a picture of the harlequin bug and a standard size toothpick for size comparison.