AP Style - bedbug
For those of you keeping score at home, AP has now decreed "bedbug" as one word to be the style.
There had been a bit of a scuffle over this, as Michael Quinion discussed recently in World Wide Words, with some folks taking the etomological position that since these were true "bugs," it should be a two-word name.
But as Quinion observed:
The rule about inserting spaces in insect common names seems to be a modern creation, an informal way of using the spelling of these names as an aide memoire to distinguish Diptera or Hemiptera species from other little beasties. It’s highly unlikely ever to affect the usual spelling of bedbug, since the tendency in modern English is to amalgamate multi-word terms into single words, not split them apart. The spelling has long since become standard for everybody except professional entomologists.