it exist a technic, quite difficult to explain, by which you cut thracic muscles with a scalpel (small ointed blade) just beneath the articulation of the wings (before setting and on relaxed specimens).
I use it for muscled moth (such some sphingid, small hard saturniid genera) and butteflies such as Charaxes and ... hesperidae ! Many collector don't like this technic (I don't knwo why as it is not visible on specimen in collection !). It needs some experience to be well done.
s'il n'y pas de solution c'est qu'il n'y a pas de problème ! akuna matata ....
Stefan, another way to set Hesperiidae is to crush the thoarax muscles with entomological forceps after it has been relaxed, then the wings can be quite easily placed into the position where you want them, this also works on more stubborn genus, charaxes, agrias etc. The body size to wing size is quite large in skippers but this makes spreading them easy, I dont have the skill or the steady hands required for the scalpel method.
Big hesperiids are never easy to mount, but a few things can make them a little easier.
First - don't store them in naphthalene. I don't know why exactly, but they never seem to relax as well if they get saturated with the stuff.
Second, make sure they are really well relaxed. I often give them a day between damp paper towels, crunch the thorax a bit, and then give them another day relaxing.
If you are collecting for yourself, don't flip them when you place them in the envelope. I know people hate bugs that die with the wings down, but that actually helps when you spread them. The wings stay pressed tight against the spreading board as you work with them (great for hairstreaks as well)
Last - you have to adjust your spreading goals to fit the bug. The attached photo shows my preferred spreading angles on the white skipper to the left (Mylon sp), and my compromise solution on a bug like Narcosius colosus. The while lines show where I would have liked to have placed the wings - but it's just not an option with a bug with this many muscles.