Dielectric properties of Rhyzopertha dominica (F.), Lesser Grain Borer with frequency range 200MHz–20GHz and Temperature range 24–65°C has been measured by using high temperature probe (Agilent). Measurement temperature points were 18. Then analyze the differentiation of dielectric properties of Rhyzopertha dominica (F.) and Malaysian paddy D219. After that the frequency-temperature distribution with the dielectric properties has been designed by using the Response Surface Method (RSM). It has been observed that the microwave 2.45GHz and temperature 48–53°C has a significant importance to disinfest the “lesser grain borer” insect.