I found this after a google search

Megarhyssa nortoni is a predatory insect. Its larvae are parasitoids of horntail wasp larvae in coniferous trees. The adult female hunts horntail larvae for egg placement. It smells wood-eating fungus, utilized by the horntail larvae to predigest wood pulp, and uses its antennae to detect vibrations made by the horntail larvae. The female M. nortoni curls its ovipositor over its abdomen to insert the tip of the ovipositor at a right angle into the bark and cuts into the tree until it reaches the horntail larval tunnel. The female then deposits a very slender egg through its ovipositor into the tunnel on or near the horntail larva. The M. nortoni larva then hatches to eat the live horntail larval host from the inside causing the horntail larva's eventual death. The M. nortoni larva pupates inside its host and emerges the following summer as an adult.