You're guess would be right. It's one of the true bugs/stink bugs called a harlequin bug. Pretty, huh? It's not a beetle, by the way.

Remove by hand and toss in a bucket of soapy water. Insecticidal soap sprays will help control them if you have a large number.

Thanks rhizo! Yes, they are beautiful but I don't have a problem picking them off and squishing them. I even found a pair mating or at least I think that is what they were doing ;) In any case, thanks for the info and clarification.

By the way...they come in other colors in case others spot them in their gardens. Yellow is fairly common.