Scanning electron microscopic study of the male genitalia of the North American alderfly genus Sialis (Megaloptera: Sialidae)

Scanning electron micrographs are presented for 14 species of the North American alderfly Sialis : americana , arvalis , californica , contigua , cornuta , hamata , iola , joppa , mohri , nevadensis , occidens , rotunda , vagans , and velata . Male genitalic characters are described for use in species identification.