Radio Sweden put the question to Marlene Hugosson, a research archivist at the Institute for Language and Folklore (Institutet för språk och folkminnen) in Uppsala.
"It's certainly influencing the tradition," she told Radio Sweden. "A few years ago there was a knock on the door. I opened the door, and outside were three little witches and an alien."
In Sweden and parts of Finland, children dress up as påskkärringar - "Easter witches" or "Easter crones" - and go door to door in the neighborhood collecting treats or money. Easter witches traditionally carry letters with greetings written on them, which are handed to neighbors.
Witches typically wear a skirt, an apron, sweater, and head scarf with bright, clashing colors. And traditionally they carry a broom and a coffee kettle in which they place their spoils.
The traditions around the Easter witches have a number of historical and mythological precursors according to Hugosson. There were witch hunts in Sweden during the 17th century and lingering beliefs about sorcery and secret liaisons with the devil long after.
Maundy Thursday and Holy Saturday, the days children go trick-or-treating, are both associated with tales about witches and their journeys to Blåkulla, (blockula in English or the "blue hill"), a meadow where the devil held court.
Hugoson wouldn't say exactly that the growing popularity of Halloween is stealing from the Easter witch trick-or-treat. But she did say the Easter witch's garb had been affected by Halloween. Nowadays, a common alternative costume features the familiar pointy black, wide-brimmed hat and black clothes typical of American witches.
Hugosson, who said she once trick or treated as an Easter witch, but who said there are fewer visitors to her home these days, blamed overcautious parenting for the decrease in trick-or-treating. But that hardly spelled the end for Easter witch traditions, she said.
"So instead we have seen how knocking on doors is sort of decreasing. But at the same time adults are organizing Easter egg hunts and Easter parades where the children can participate," she said.