Those dratted things usually show up later in the year for me. I usually hand pick them and put them in a bowl of soapy water. I do the same with those terrible squash bugs!
I also have a spray bottle of water and some soap for spraying directly on the bugs. They will fall and die. The soap breaks down their waxy coating. It's not immediate but it is very effective. I wear gloves since they do emit a stink and because I don't really like touching bugs... I only like taking their pictures.