I supose it comes down to an ethical debate. And not the ethics of the killing the insects part. Knowingly faking a photo and presenting it as real life.
I know it is done in other photography.... zoo shots passed off as wild Africa... or anywhere else. Nothing wrong with zoo shots..... except for passing them of as real. Some famous "nature shows" are guilty of using footage of zoos for "wildlife shots"
I saw a photo the other day on "imagekind" (but it doenst matter where, it could have been smugmug.... flickr... whatever.) of a fox against a red forested background, that I'm sure was taken with a wide angle lens, and the foxes head was full frame...... which looked "stuffed" by that I mean the fox looked like it was stuffed. There was something just not right about the eyes. Coupled with the fact the photographer must have been within inches. Totally possible, I don't doubt, but the photo looked fake, very. My initial reaction was not "look how close he got to that fox" it was "boy that looks fake" But the person was saying it was real in the description. I don't want to commit libel, so I won't show it to you.... not that I could find it again. Plus it's not really the point.
The point is taking a pic of a dead but and passing it off as alive, is just so wrong. Despicable even. Nothing wrong with taking a pic of a dead bug, and saying here is a dead (X) ... but to pass it off as real... total BS.....sorry that is how I feel. Mush like how I feel about aforementioned zoo "wildlife" shots. Some people may think I'm comparing apples to oranges, but I think they are similar ethical boundaries.
I will agree with archer, about the refrigerator. Not unethical, even from a humane or genuine article standpoint. There are always tricks you can do without crossing ethical borders.