This research was carried out in Kermanshah province for two years (1984-1985). Sugar beet loss assessment caused by flea-beetle was studied on leaves and some insecticides were tested on adults. Results showed that, when one flea feeds on one or two plants, damage is low on leaves, but when two and three fleas feed on one plant in comparison with an unfed plant, results are as follows: -when there isn’t any flea on plant from 2-leaf stage up to end of 6-leaf stage, average No. of leaves is 6, length and width of leaves are 3.13 and 0.93 Cm. respectively and the rate of infestation per plant is zero. -when there are two fleas on one plant in same stage, average No. of leaves is 5.25, length and width of leaves are 2.13 and 0.7 cm. respectively and the rate of infestation per plant is 3.35 (more than medium infestation). -when there are three fleas on one plant, average No. of leaves is 4.5, length and width of leaves is 1.02 and 0.48 cm. respectively and the rate of infestation per plant is 4.45 (more than high infestation). To determine the effective and suitable insecticide some of them were chosen out of various groups of chemicals and tested on adults. The most effective types and dosage were: Phenvalerite 20% , 750 cc and phosalone 35% 3 litres per hectare.
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