sippyjug104 wrote:
This is a 10X magnified focus-stacked view of the green bottle fly's calypters which are located under the forward portion of the wing where it joins the body. Flies that possess calypters use them to cover the 'halteres' which is the little "paddle-like wing" that aids the fly in maintaining stability in their flight. A crane fly is an example of one that does not possess calypters which makes their halteres visible when they are at rest.