I guess house yu's in this canon aren't very tiny like other artists make them, otherwise you could just put it in a container that only the roach-yus are small enough to get food from. Then again, geniuses like this Silver Reimu would still somehow jam their tongues inside the bait container and lick it out.
Although pet yukkuris are obviously larger than house yukkuris and have a higher lethal dose, their risk of dying is still high in case of accidental ingestion.Although pet yukkuris are trained not to eat strange food, it's impossible for yukkuris to raise suspicions about food found in "their own easy place". Even a outstanding gold-badged yukkuri can't do this.Be ineffective against pet yukkuris while remain effective against house yukkuris.
There is a voice that asks for repellent born from this obvious contradiction.*Shock*Can't...mobe...Yu!
A tribute from Mister!Yu...ga...*-tle**Rus-*YUBy destroying paste cores and solidifying body pastes,
they always finish expelling after a single intake.