noun
meddler; interferer; buttinsky
Playful, mildly critical term for someone who intrudes or interferes, often used in a lighthearted or teasing way. Literally 'nuisance bug'.
彼はいつも人の話に口を出す、本当にお邪魔虫だ。
He always butts into other people's conversations; he's a real meddler.
デート中にお邪魔虫が現れ
A buttinsky showed up during our date, so we couldn't be alone.
Compound of お (honorific prefix) + 邪魔 (nuisance, hindrance) + 虫 (bug, used figuratively for a person with a certain trait). The exact origin is uncertain, but it likely arose as a humorous, colloquial expression.