Description_x000D_ Application_x000D_ IPL-41 is part of a series of media originally developed at the USDA Insect Pathology Laboratory by Weiss et al. for the large scale propagation of cells from the fall armyworm, Spodoptera frugiperda. The medium is primarily used for the growth and maintenance of cell lines derived from lepidopterans and the propagation of viruses in these cell lines. One of the most significant uses of the medium is the large scale culture of baculovirus infected Spodoptera cells. The expression of recombinant proteins is undertaken from Spodoptera cells utilizing the baculovirus expression system (BEVS). Attempts have also been made to obtain the expression of foreign genes in cells cultured in IPL-41 without serum supplementation.