Population density of the beet fly, Pegomia mixta Vill and the beet weevil, Lixus juncr' Bohr were studied on the chard and the dock weeds growing normally in sugarbeet fields at Fayoum Governorate during the growing seasons of sugarbeet crops 2001/2002 and 20032003. In general, the highest peaks of abundance of P. mixfa eggs and larvae was occurred on the chard weed during the period extended from 0‘“ of Feb. to 27‘“ of Apr. and from a“ of Mar. to 27‘“ of Apr. in the 1"t season; from 213m of Dec. to 3'“ of Man, respectively. The counts of the eggs and larvae showed that infestation of P. mixta vill occurred firstly on the chard weeds then transmitted to sugarbeet plants. As for the eggs and larvae stages of the beet weevil L. fund, the highest peaks of abundance was occurred on the dock weeds during the period extended from 18"1 of Mar. to 7“ of Apr. and from 18Ih of Mar. to 1?"'1 of May in the 1"t season, respectively. Also in the 2"d season the total number of eggs and larvae was high during the period from 13':h of Mar. to 2Ml of May and from 23rd of Mar. to 22"" of May, respectively. Results indicated that the weed acts as a suitable alternative host and direct source of P. mixta and L. junci infestation to sugarbeet plants. So, clean cultivation and removal of the chard and the dock weeds could be minimized the population density of P. mrbrfa and L. juncr' on sugarbeet plants. Sugarbeet variety Betapoly 4 infested with highest numbers of P. mixta, while Gitane variety received the least numbers in the 1" season 2001/2002. Also, kawsa 12 variety harbored the highest numbers of P. mixr‘a in the 2"‘1 season 200212003. The highest numbers of L. junci occurred on Betaboly 4 variety during the two seasons 2001/2002 and 20032003. Also, there was no effect of the total numbers of predator, Chrysopefa cornea and true spider on the total number of P. mixta eggs.