"Being associated with a ceann féile (cheif festival), May Eve and May Day were supposed to be times of greater than usual activity among supernatural beings, Every lios ("fairy fort") in Ireland was said to be opened that night, and their inhabitants moved abroad in great numbers, often changing residence at that time."
- Seán Ó Súilleabháin, 'Nósanna agus Piseoga na nGael'
Hawthorn in the spring rain
Bealtaine has many different themes and associations in folklore but one of the strongest is the idea of the presence of supernatural beings being particularly strong at this time. For example one belief was that on Bealtaine day it was wise not to lend out any milk, butter, or a coal from the fire, especially to a stranger, lest the person be one of the Good Folk in disguise and steal the family's luck for the year (Wilde, 1888; Evans, 1957). A household's luck was intrinsically tied to the items which symbolized it - milk, butter, and fire - and to be tricked into giving any of these to dangerous powers including witches or the Fair Folk was to voluntarily give them power over you; to do this particularly on Bealtaine when spirits of all kinds were abroad and their powers especially strong was the height of foolishness.
As the quote above illustrates every sí was believed to open and the inhabitants to travel out across the land, a process which was repeated as well at Samhain. Bealtaine was also the time when babies and young brides were most likely to be taken and a person had to take great care when travelling, especially alone. Although today many people might think of Samhain as the most dangerous liminal time, in truth Bealtaine was equally dangerous and liminal. At other times of the year a person might still run the risk of running afoul of the Fair Folk - or if one was lucky and clever of earning their blessing - but at the turning points like Bealtaine every single one of my references all mention the ubiquitous presence of the Other Crowd, to the point that it was almost expected to see or experience something Otherworldly. To quote Danaher:
"Supernatural beings were more than usually active about May Day, and the appearance of a travelling band of fairies, of a mermaid, a púca or a headless coach might, indeed, cause unease or alarm but certainly would occasion no surprise, as such manifestations were only to be expected at this time." (Danaher, 1972, p121)
There were two main, and possibly interlinked approaches to dealing with the Daoine Eile on May Day. In the old days - and perhaps still in some places - it was traditional to make offerings on May Day morning of milk poured at the base of a fairy thorn or on the threshold of the house, and to take the cows to the sí and bleed them, with some of the blood tasted by the people and the rest given as an offering to the Daoine Uaisle (Evans, 1957). I personally try to avoid making blood offerings during most of the year, but some exceptions may occur on the major holy days, and we see a precedent in both Irish and Norse belief of offering such to the aos sí or elben respectively*. Any offering of food or drink, left on the doorstep of the house or at any known Fairy place, whether its a lone fairy tree or fort, was also done and was thought to convey some protection on the person (Danaher, 1972). I would also suggest that offerings of butter, bread, or cakes would be in line with tradition and acceptable. Offerings are an important part of creating a positive reciprocal relationship with the powers of the Otherworld. One might note that there is an important difference between being tricked into giving milk or butter without intent and giving the same things purposely as gifts; to be tricked is to lose your power but to give a gift freely is to show respect and hopefully create an amicable relationship.
Protections against harm from the Other Crowd included primrose and gorse scattered on the doorstep, and Rowan branches hung over the doorway (Evans, 1957). Yarrow was hung in the home to ward off illness, and a loop of ash might be used to protect a person against Themselves; it was also said looking through the loop would allow someone to see them even through glamour (Evans, 1957; Danaher, 1972). Iron should be carried, ideally a black handled iron knife, or else ashes from the hearth fire, and if one is being misled or tormented by the Good People one could turn their jacket inside out to confuse them or in more dire circumstances they could splash urine on their hands and face* (Danaher, 1972). Of course the most commonly used protection may simply be staying inside and avoiding any chance encounters.
At Bealtaine some people say that the veil between the worlds is thinner; I disagree. I think that at Bealtaine and Samhain both it is not that the separation between the worlds is any different but the amount of presence in our world is notably higher for those who are aware of such things. So be sure to pour out a little milk or cream for the Good People and if you are out and about carry a bit of salt or iron in your pocket, and hang a bit of rowan with red thread over your doorway.
And don't be surprised if you see something uncanny.
*In Grimm's Teutonic Mythology he discusses the practice of offering a cow to the elves as part of an alfablot
*The Good People detest filth and things like dirty wash water and urine are known to disgust them, and so act as protections against them.
Ó Súilleabháin, S., (1967). Nósanna agus Piseoga na nGael
Wilde, E., (1888) Irish Cures, Mystic Charms & Superstitions
Evans, E., (1957). Irish Folk Ways
Danaher, K., (1972) The Year in Ireland