The relative susceptibility and monitoring of nine widely spread citrus species / varieties: Navel orange, Balady orange, Valencia orange, grape-fruit, Balady Mandarin, lime, Lemon, Sour orange and Volkamer lemon to the wasp beetle, Chlorophorus varius (Coleoptera: Cerambycidae) borer infestation as well as the population fluctuations were studied at Sharkia governorate, during the three successive years 2010, 2011 and 2012. The mean rate of susceptibility of citrus species and varieties to C. varius infestation reached 32.5% (range, 5.0 – 55.3%). The grand mean degree of susceptibility of citrus species / varieties to C. varius infestation approximated 0.6177 beetles / tree / year. Infestation increased from 0.52 beetles / tree at the end of 2010 (one year), to 1.123 beetles / tree at the end of 2011 (two years) to 1.853 beetles / tree at the end of 2012 (three years). Summer months recorded the maximum beetle flight (0.3677 beetles), followed by spring (0.1241 beetle) and autumn months (0.1148 beetles) /tree, but stopped during winter. The grand mean degree of susceptibility of citrus species / varieties to C. varius infestation approximated 0.1533 beetles / tree / season. Generally, Navel orange proved to be the most susceptible species followed by Balady orange, Valencia orange, Grape fruit, Mandarin, Lime, Lemon, Sour orange and at last Volkamer Lemon. Infestation increased from 0.13 beetles / tree at the end of 2010 (one year), to 0.28 beetles / tree at the end of 2011 (two years) to 0.46 beetles / tree at the end of 2012 (three years), that impose the need to control this pest in citrus orchards.