This is a large wasp of family Ichneumonidae. They are very noticeable because most of them have very long ovipositors extending from the abdomen. When I caught this Ichneumonid, the abdomen was a very bright red, but after pinning the abdomen became a duller red color.
These wasps are parasites of other insects, specifically their larvae. When the wasp locates the grub, sometimes several inches inside a tree or the ground, the wasp inserts its ovipositor and lays an egg in the grub. The insect's body, not including the ovipositor, tends to be fairly large and thin, at least an inch long. Ovipositors can extend beyond the length of the insect's body, as in this example.