Red-shouldered Bug – Identified
Q: We have hundreds of insects in our yard and we don’t know what they are. I went to a big box store and stumped their gardening experts with it as well. They congregate in large groups. As far as I can tell they are not killing any plants. They like to crawl on the side of our brick house.
A: Two very similar insects emerge in mid-March each year. One is box elder bug, which congregates under box elder maple trees, and red-shouldered bug, which is usually hangs out near goldenrain trees.
You have red-shouldered bug.
Neither insect is harmful, except for the aggravation factor when they crawl into your house.
They make a nice snack for birds so my advice is to leave them alone until natural forces have a chance to control them.
see Box Elder Bug Identification and Control