Cosmopterix parandella Riedl (Lepidoptera: Dosmopterigidae) is a new recorded pest species on sugarcane, Saccharum officinarum L.. in Egypt. At Al-Aiat region in Giza govenorate, was sampled from May to December in 2001 and 2002. Eggs are laid individually on the outer mar­gins of the upper surface of the leaf midrib. Newly hatched larvae mine into the midrib feed on tissue leave brown tunnels with longitudinal patches on the other side results in easily broken of leaves which turned yellow and drying early. Mining tunnels extend from thin lines to wide as larvae move forward feeding and growing up. At the terminal end of mine, the full-grown larvae pupated in a chamber with covered circular opening for moth emergence. Moths developed from overwintering lar­vae are considered the main source of the new infestation by early May on ratoons in the old infested fields. Infestation reached 15.8 and 12.3% by late May and continued until late December with a peak of 28.5 and 24.6% by the first and the third weeks of June in the new growing fields in 2002 and 2001. In general, infestation rates were 9 and 9.5% and in­creased to 15.4 and 16% on infested plants in 2001 and 2002 with 106 mining tunnels/100 infested leaves in both years. The highest mine den­sities and infestation intensities113 and 114/100 infested leaves and 22.6 and 30.7% were recorded during the second half of May-early June and the first three weeks of June. Mining tunnels ranged between 1- 4 per infested leaf and distributed on the ten upper leaves. Leaves of 1 and 2 mines accounted for 94.5 and 5.2% of the total mines and the second leaf on the sugarcane plant received the highest midrib miner in­festation 29.3%. Negative relationship was detected between the num­ber of leaves on sugarcane plant and the degree of infestation by the midrib miner. Plants of 3 and 4 leaves harboured the highest infestation rates (36% and 35.6%) in both seasons of study.