Hi. The larger insect is probably a brown marmorated stink bug and the smaller one is some kind of weevil. The BMSB is a relatively new invasive pest in MI but I cannot see all the identifying marks from your photo. Both of these pests would cause chewing damage on the leaves. I am unsure of what you mean by a sweet pea bush. Sweet peas in our zones are usually vines. There are several things that could be wrong with the plant, from poor watering to a wilt disease. If a picture could be sent of the plant where it is growing that would be helpful. Going to http://www.pestid.msu.edu will give instructions for sending a sample to the MSU lab for diagnosis, if the client would like to do that. The insects may be present because the plant is under stress.