Ground shield bugs (Choerocoris paganus) like them too. They feed on seeds as they develop. When disturbed, the bugs usually drop to the ground and scuttle away but these two were obviously preoccupied.
It's easy to mistake shield bugs (family Scutelleridae) for beetles. In most bugs the scutellum is a small triangular plate that sits between the wings. You can see it clearly in this picture of harlequin bugs (Dindymus versicolor). It's nothing to write home about. But in scutellerids, it is greatly expanded, often covering the wings. This gives them a beetle-ish look.
A couple of earlier posts here and here give pointers to distinguishing between bugs and beetles.
