Hello,

This was one of our most asked questions in the fall, and it was a featured question on our website: https://extension.oregonstate.edu/ask-expert/featured/stink-bugs-boxelder-bugs-everywhere

I suggest checking out the answer. Let me know if you'd still like to connect with an entomologist.

Last summer and fall produced a bumper crop of box elder bugs in many places across western Oregon. The bugs you are seeing now are from that generation that overwintered. They are now getting active and looking for box elders and maples to lay their eggs, but with the still cool temperatures, the bugs will congregate in warm spots (like your south facing walls). 

You can hose them off with a strong spray of water, but it's likely new congregations will form until warmer spring weather sets in. Once the weather warms, they will disperse. Then they will start congregating again in the fall. Whether you see big groups in the fall depends on how big the populations get over the summer. 

Other than being a major nuisance, the bugs aren't really harmful. 

This webpage has some additional information: https://ipm.ucanr.edu/PMG/PESTNOTES/pn74114.html