It is not really "Fledermaus" that they are doing at Wolf Trap this week. It is unfortunately a version that has persisted for about 60 years, in which the great Strauss score is mangled in a ludicrous translation that slows down the action umercifully while offering jokes that were exhausted when vaudeville was in flower. Some of the music has been messed up by Erich Korngold, who should have known better.

There is a ballet at the beginning which ruins the effect of Strauss' sparkling overture. And weirdest of all, the ghost of Johann Strauss Jr., the composing genius, appears from time to time during the operetta, all in pale white, looking like the ghost of Viennas past. It is a shame, since the production boasts some excellent singing, a fine chorus, and a beautiful second act ballet.

If "Feldermaus" is to be stretched out to almost midnight with tired lines and insertions that tend to wreck Strauss' greatest operetta, that at least it should sparkle. This the Wold Trap production cannot do because of what Franz Allers offers under the guise of conducting with a ragged, coarse-sounding orchestra. There is no pluse in the great moments, no rhythm that lasts long enough to lift your feet and hands. Karajan, Kleiber, Krauss, and Ormandy -- to name only a few -- have shown us what "Feldermaus" truly can be.

Among the stong points of the unusually handsome show are the sets and costumes, the dancers of the Washington Ballet, headed by Terry Edlefsen and Sylviane Bayard, and the strong cast of principals. And even here there was a problem in the cruel over-amplification of the voices. Erie Mills is an enchanting singer who is ideal as Adele. She came out sounding like Birgit Nilsson. Howard Hensel's Eisenstein is a polished study, beautifully sung, but sounding as if he were working the Caruso belt.

Anna Moffo is a seductive-looking Rosalinda, knowing every trick of the business, and her singing matched her acting. These were surrounded with the outstanding Falke of Jake Gardner, Christopher King's Blind, and Steven Willeman's Frank. Jerome Pruett was all that Alfred needs to be, high A and all. Jack Harrold was given far too much camping as Prince Orlofsky, which made up only in part for his less-than-singing. And in the last act, Jack Guilford felt no constraints in taking over in his famous portrait of the jailer. But friends, do not think you saw and heard "Fledermaus."