State transportation officials are scrambling to allay fears that the four-lane expressway planned between Marshalltown and Des Moines will NOT be completed on schedule. A rare butterfly has been discovered along the corridor, and the highway’s path MAY have to be altered. DOT spokeswoman Dena Gray-Fisher.says the Mulberry Wing butterfly, which is a protected species, was seen laying eggs in a marsh along the highway route. Gray-Fisher says the D.O.T. will delay re-construction of the area beside the marsh.Until the butterfly issue is resolved, construction crews will work on the other areas of the highway.A few years ago, state officials working to keep Lennox Industries expanding in Marshalltown promised to step-up construction of an expressway connecting Marshalltown to Des Moines.