Materials examined. 2 males from flight feathers of the common swift, Apus apus (Linnaeus, 1758) (Apodiformes: Apodidae), Samsun, Türkiye, 10 May 2022, coll. M. Öztürk (as shown in Fig. 3).
Remarks. The genus Eustathia includes nine described species associated with birds of the order Apodiformes in the Old World (Europe, Africa, and Asia) and the New World (North America and South America). In the previous studies conducted in world, Eustathia cultrifera has been reported on the African black swift Apus barbatus, the common swift Apus apus, the little swift A. affinis, the white-rumped swift A. cafferhas, the Horus swift A. horus, the Pacific swift A. pacificus, and alpine swift Tachymarptis (Apus) melba been reported (Kwanyuen, 1973; Peterson et al., 1980).