The band are shocked by her sexualised routines and whipped cream bra, and have expressed particular disgust with the fact that she markets herself to children.
Speaking to NME, singer Alice Glass said, "I think a lot of (pop stars) sell sex to children. I think a lot of kids are more sexualised now than they were years ago and I'm not sure it's a coincidence.
"Like f**king Katy Perry spraying people with her f**king d**k, her f**king c** gun c**ming on f**king children. And little girls, like six-year-old girls wearing a shirt with 'I wanna see your (pea) cock' on it."
Keyboard player Ethan Kath agreed with his bandmate, saying, ""On the merch (merchandise) for that song Peacock, the 'Pea' is on a different line so you don't see it. She sells it to f**king children."
And Glass wasn't finished with her rant, as she added, "It's f**king evil. Don't prey on vulnerable people like that.
"Don't encourage little girls to get dressed up, to have cupcakes on their t**s to get people to lick them off, 'cos that's what you're insinuating."
Katy Perry: Hopefully not 'selling sex' to these girls on The Ellen Show, then.
This is far from the first time that Katy Perry has been criticised for her antics. Earlier this year, stand up comic Sarah Kendall also expressed her distaste at the singer's sexualised videos.
The Australian comedienne told Stylist: "There's a whole generation of women who don't care about feminism.
"A lot of younger women think 'lezzing off' for the boys is equal rights. It's not!
"Little girls are obsessed with Katy Perry. Her videos are full of phallic symbolism; liquid shooting out of tubes, lollipops, hairbrushes by the mouth. It all looks very BJ..."
Watch the sexy video for Katy Perry's 'California Gurls' below:
And check out the most sexualised videos - from Katy's cream to Azealia's sausage