The earliest description in print is William Kennish's, in the poem Old May Eve in his Mona's Isle of 1844, written as a Maughold man remembering what old Manxmen had told him. When the eleventh of May came round, each horse was stalled, the cows were called home before sunset, and the sheep were driven off the mountain into the yard, so that they might be spared from witches by counteracting skill. The rank bolugh, a yellow meadow weed thought to have a charm against witchcraft, was strewn along the cow-house floor and round the threshold of the door, and crosses of the rowan tree were formed by the young men and tied to each cow's tail and round the lintels of the byre, to further check the witches' fiendish ire if the bolugh charm should fail. For if the witches once laid their spell on the cattle, they would pine away by slow degrees and baffle all the goodwife's skill that year to fill her butter crock or make a cheese. Joseph Train, a year later, added the Manx name. In former times, he wrote, small crosses were made of twigs of the mountain ash, called in Manx crosh keim, and disposed over the door of every dwelling house, stable and sheepfold, with a piece of iron of any description, and made fast to the tail of every cow.

The date is Old May Eve, the night of the eleventh of May, the eve of Laa Boaldyn reckoned by the old calendar, when fairies and witches were held to be more active than at any other time of the year. William Harrison reprinted Kennish's lines in the Manx Society's Mona Miscellany in 1869 and glossed the bolugh as the mugwort. A. W. Moore, in 1891, gave the custom in the form in which it is now generally told. On May Eve green leaves or boughs and primrose flowers were strewn on the threshold, and branches of the cuirn, or mountain ash, were made into small crosses without the aid of a knife, which was on no account to be used, and stuck over the doors of the dwelling houses and cow-houses. He recorded that a branch of the cuirn in the cow-house on May Eve was one of the most efficacious charms to prevent milk being bewitched, and that on Good Friday a stick of cuirn was used to stir the fire in place of the iron poker. The tree, he thought, had been regarded with special veneration. It was planted with the thorn and the ash beside the sacred wells, where votive offerings had been placed within living memory, and its leaves, like those of the elder, were picked on May Eve and fixed to doors and windows against witchcraft.

John Rhys, collecting in 1891, found the same practice in use. On Old May Day systematic efforts were made to protect man and beast against elves and witches, and people carried crosses of rowan in their hats and placed May flowers over the tops of their doors, while crosses of rowan were fastened to the tails of the cattle, small crosses which had to be made without the help of a knife. He exhibited a specimen at a meeting of the Folk-Lore Society. A twig of cuirn, he added, was as effective against fairies on the Island as in Wales, and he traced the word to Irish caorthann and Scottish Gaelic caorunn, the same sacred rowan that lies behind the old Irish names Mac Cairthinn and Der Chairthinn. William Cashen of Peel, whose notes on the fishermen were published by Moore in 1895 and gathered into his Manx Folk-Lore in 1912, carried the cross to sea. On May Eve the crosh cuirn was put into every boat. The men would travel for miles into the country to get it, and would deposit it in some secret place in the boat, where it had to remain until the following May Eve. In the cottages of his youth the crosh cuirn was always behind the door, renewed every May Day Eve, and no evil thing could pass in where the crosh cuirn was.