Here are some excerpts from my essay on the subject:
In Frank Edwards' Strangest of All and Morris K. Jessop's Case for the UFO, the boy's name is Oliver Lerch, but in C. B. Colby's Weirdest People in the World, where I first came across it, and John Keel’s Our Haunted Planet, the boy's last name is "Larch". Well, what's one letter off, more-or-less?
Brad Steiger's Strangers from the Skies: "It was on Christmas Eve, 1909, that 'they' took 11-year-old Oliver Thomas up into the sky." Wait -- what? Young Oliver Thomas of Rhayader, Wales, sent out to get a pail of water, started screaming for help. The gathered family and guests rushed outside, only to hear his voice echoing down from high above. His footprints made a trail across the yard for about 75 feet, then they stopped abruptly. "There was only one conclusion that the authorities were able to render: Oliver Thomas had inexplicably vanished -- straight up." [Steiger, pp. 33-34]
Finally, and perhaps inevitably, we reach way back to American literary celebrity Ambrose Bierce and his story "Charles Ashmore's Trail," one of the vignettes that form "Mysterious Disappearances." It seems that the family of Christian Ashmore lived on a farm in Quincy, Illinois, in the nineteenth century:
"On the evening of the 9th of November in 1878, at about nine o’clock, young Charles Ashmore left the family circle about the hearth, took a tin bucket and started toward the spring. As he did not return, the family became uneasy, and going to the door by which he had left the house, his father called without receiving an answer."
The Lerch version appeared in Fate Magazine (September 1950) under the title “What Happened to Oliver Lerch?”, by Joseph Rosenberger. It is this version that most later writers took as a source. Joe Nickell, a researcher known for exploding numerous modern myths, tracked down Mr. Rosenberger and interviewed him. Rosenberger admitted the tale was false, written out of a need for money. “Every single bit is fiction. I wrote the damn piece way back when, during the lean days.” [Shoemaker, p. 21; Paijmans and Aubeck, p. 43]
The strange thing is, the confession of a hoax is itself a hoax. Theo Paijmans and Chris Aubeck, checking many back issues of newspapers and magazines, discovered several references to the Lerch story before 1950. The original version was apparently one that appeared in the New York Sunday Telegraph, December 25, 1904, written by an Irving Lewis. This early and elaborate version gives a list of names at the end, witnesses to the tragedy that signed an affidavit as to the truthfulness of the matter. As you might guess, further research failed to prove that any of these witnesses – or the Lerch family itself – ever existed. Presumably “Irving Lewis” lifted the story idea from “Charles Ashmore’s Trail.”
Paijmans, Theo, and Chris Aubeck, “Nightmare Before Christmas: The Strange Disappearance of Oliver Lerch,” Fortean Times no. 335 (Jan. 2016), pp. 42-47.
Shoemaker, Michael, “Three Discoveries in Fortean Folklore,” INFO Journal no. 66 (June 1992), pp. 20-21.