Most people I know refer to buterflies just by their specific name. It's short, easy, universal (important on the continent) and has just as familiar a feel. A lot of the English names of European butterflies were simply invented on the spot by Higgins & Riley because they felt a book for the general public needed common names - so they don't have any real history or authority. That's not true of the names of British butterflies, of course.
The biggest problem is pronouncing the names! Zoological Latin is pronounced in English quite differently from any form of real Latin or any other European language!! Pete has included sound files of suggested pronunciations of each species on this site and these are very good.
On which point, why do they always pronounce
C. difficile on the television and radio as if it were French? It should rhyme with 'smiley'.
Guy