long the cash fly ~ short the belly, long the wings.
long the swap fly ~ pay the belly, receive the wings
check me on this if I am wrong please.
In rates it is good to think in terms of rates and talk in terms of bonds. Just about for everything including delta and options skew even (on certain desks).
Only quants and pure "interbank derivatives" people will talk in terms of rates. If you work in a place that is somewhat close to the actual underlying rates instrument, which is a bond, it's custom the way I described.
A side effect of this is that for example derivatives people refer to CMS spread options as "CMS spread options", but this is an unfortunate name, as a spread is typically referring a basis. A better name is "CMS curve option".