We found this on our farm in central Nebraska early this morning. It was in dirt near a building. It is very shiny and has a triangle marking on its back. I’ve looked at several photos on the web but have not found one that looks like this one. His antenna seems smaller than most I’ve seen. We had it in an large ice cream bucket and it flew out of it. Thanks in advance for your help.
Based on the size and keel on the underside, your beetle is the giant black water scavenger beetle. Thanks for all the great photo angles!
Do you have a pond on the farm? These beetles live in weedy ponds or lakes. Since they come to lights at night…it might have flown in to a night light you have near the building?
Water scavengers have keeled sternum – that long narrow pointer that you can see on the underside. They come up for air head first while predaceous diving beetles do not have the keel on the sternum and come up tail first. Also if you could see them swimming the water scavenger swims alternating the hind legs while predaceous diving beetles hind legs go in unison like oars.
These beetles feed on dead decaying aquatic animals – hence scavenger in the name. :-)They help keep the ponds clean!
The larvae are predatory feeding on other insects and small aquatic animals.