Late juvenile with endoparasitic worm that emerged from it; Chester County, Pennsylvania.
Photograph by David H. Funk, Stroud Water Research Center, used by permission.
Worms similar to this that emerge from Orthoptera are either mermithids (Nematoda: Mermithidae) or
horsehair worms (Nematomorpha). This is a mermithid, and this is University of Florida nematologist
Khuong B. Nguyen's advice on how to tell the difference: Place the worm on a glass slide
and inspect under a microscope. If you can see through the body with some structures
inside (especially at both ends), it is a mermithid. If you cannot see through the body,
it is a nematomorph.