In US, ichneumon is an insect larger than a wasp, with an ovipositor longer than its body.

hat larval Ichneumon can prey upon other insects is possible because of the method by which the
adult female lays its eggs. Mated adult females fly from tree to tree, pressing their long antennae
against bark to detect vibrations made by insect larvae. Having found life underneath the bark,
she curls her ovipositor up over her abdomen, then curves it down to enter the bark at a right
angle. The sharp tip cuts into the bark until it reaches the larval insect tunnel. An Ichneumon
egg is then inserted into the tunnel, where it will hatch and feed upon the host larvae until it
develops into a mature larvae itself.

I used to think the ichneumon dmaged the tree. Maybe they actually benefit ;the tree.