How do you use the word insidious in a compound sentence?

Really bad diseases trasnmitted into the body can be insidious with harmful effects.

as for symbolic actions, the narrator's tearing down the wallpaper in an attempt to find the "woman" in the wallpaper represents her struggle to retain or regain her sanity.   the wallpaper has been part of her confinement and by her tearing it down, she is freeing herself from that confinement.

it would be offer because the group is offering all at once.