Rhyssinae is a subfamily of parasitoid wasps in the family Ichneumonidae. It contains eight genera and 259 described species, but there are likely many undiscovered species.

All possess long ovipositors, which are used by females to bore into tree trunks to lay eggs on the larvae of horntails and wood-boring beetles.

Females in genus Megarhyssa show very long ovipositors, with the one of M. atrata reaching 14 cm in length.

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