Passandridae

Passandridae, the parasitic flat bark beetles, is a family of nine genera and 109 described species whose larvae are exclusively ectoparasitic on the immature stages of other beetles and of Hymenoptera. Adults are 3 to 35 millimeters long, heavily hardened, brown or black, with prominent mandibles and grooved backs; only the genus Passandra occurs in both the Old and New World, while the others are restricted to one hemisphere. The oldest known fossil, Mesopassandra, comes from mid-Cretaceous Burmese amber roughly 100 million years old. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/