Cleptoparasitic: Hosts Megachile (Chalicodoma) parietina, M. pyrenaica and Hoplitis pallicornis. Banaszak & Romasenko (1998) additionally cite Hoplitis adunca, Hoplitis anthocopoides, and Megachile (Chalicodoma) sicula.
J.G. Rozen, Jr. & H. Özbek (2005) state that the species is a cleptoparasite of Osmia cerinthidis in Turkey. These authors also state that the female Dioxys deposited her egg before the host female closed the cell.
Baldock et al (2018) report the species being found at a nest of Hoplitis benoisti in Portugal