Ichneumon Wasps have over 3000 known species; these of the genus megarhyssa are two of the largest—eight to ten inches in total length.
The long whip-like ovipositors on females enable the wasp to penetrate the host wood through small openings in the stump and lay eggs on the resident grub.
Larvae of most of the wasps are parasitic in moth and butterfly caterpillars. Two of the largest, as these in the video, are parasitic in the grubs of horntail wasps.
How they locate the host grub remains a mystery-- they seem to be probing, using their antennae prior to penetrating the wood to lay their eggs.
Although frightening in appearance the two wasp species shown here are harmless to humans as they are not equipped with stingers. Such is not the case with all of them!
Music: "Bring Back Stubbies" by Derek R. Audette