Sitting on the hillside under an oak, watching trail users go by from a good ways off!
I used the key from
Krombein, Karl V. “Studies in the Tiphiidae (Hymenoptera Aculeata): IV. A Revision of the Myrmosinae of the New World with a Discussion of the Old World Species.” Transactions of the American Entomological Society (1890-), vol. 65, no. 4, 1939, pp. 415–465. JSTOR, www.jstor.org/stable/25077448. Accessed 14 June 2020.