Wood or other bees in horse stalls
Please see attached pictures. We seemed to have wood bees in our horse stalls. They were very visible flying around outside. I got rid of them by using this trap https://www.amazon.com/gp/product/B01ACDF5YA/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1 and putting a noise source in the stall area. I never did find any boring holes (see picture - likely a knot) but there is evidence of something digging into the stall dirt floor. There are piles of grey matter all over the floor. It is most prevalent along the base of the wall. I have not seen any insects or animals near these grey piles. What is causing this and how do I get rid of them? Thanks.
Yes, the first photo looks like a wood knot. The bees you describe outside sound like carpenter bees. They would not dig in your stall floor. Ground dwelling bees make holes that are easily visible, so the middle photo does not appear to be them. It looks more like the signs of ant activity. Ants tend to tunnel, churn, and kick out subsoil. Though we don't see any holes in these photos (maybe one), the gray granules look like the stone dust often used as a base for horse stalls.
The third photos may be ground bees. (though, what would be white in the soil--lime?) Lime would not be good for bees, and you may find that activity stops shortly.
Here is our website info on ground bees: http://extension.umd.edu/hgic/mining-bees-lawns
Mining bees, as well as carpenter bees, are very docile. The males have no stinger at all. The females are not aggressive at all. Because they are important pollinators, we recommend that you leave them alone if possible for their short lifespans, so that they can pollinate.