Retired University of Louisville Professor Charles Covell and others will again lead a butterfly counting expedition on Saturday morning in Oldham County. The count, held annually at U of L’sHorner Wildlife Sanctuary, is part of the national butterfly census.Covell says a butterfly’s habitat is delicate and can be affected by factors such as the harshness of the previous winter, and environmental changes brought about by human activity.“Certain kinds of wildflowers that we expect to find butterflies on are much less common now than they were maybe 20 years ago," Covell says.Volunteers are encouraged to help with the count, and instruction on how to identify the butterflies they see will be provided.