The present investigation was carried out at Kafr El-Sheikh region during 2008 and 2009 to survey lepidopterous stem borers on the main graminaceous weeds as well as on the botanically-related economic crops. Graminaceous weeds were found to harbor several lepidopterous stem borers at Kafr El-Sheikh region. Common reed (Phragmites australis Trin), harbored Sesamia nonagrioides Lef., Mythimna crenulata Hampson., and Chilo luteellus Mosts., Torpido grass, (Echinochloa stagninum Beauv.), harbored Sesamia wiltshirei Rungs and Chilo agamemnon Bles., while mat sedge (Cyperus alopercoides Rottb.), harbored Eldana saccharina Walk. During the course of the current study three stem borers (Sesamia cretica Led., Chilo agamemnon Bles. and Ostrinia nubilalis Hubn.) were recorded on the main graminaceous crops; sugarcane, rice and maize. These borers hibernated from November to April and were active during other months of the year. Lepidopterous stem borers can be placed in three categories according to time of dormancy: 1- Borers active all the year round and has no dormancy, e.g. S. nonagrioides, 2-Borers which aestivate in summer, e.g., M. crenulate and S. wiltshiere and 3-Borers which hibernate in winter, e.g., C. agamemnon, C. luteellus, S. cretica, E. saccharina and O. nubilalis.