eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2016-05-03 7 2 579 588 8842 article Khalid M. Al-Ghamdi 1 AbdulRahman A. FarajAllah 1 Habeeb M. Al-Solami 1 Department of Biological Sciences, Faculty of Science, King Abdul-Aziz University, P.O Box: 80203, Jeddah, 21589 (Saudi Arabia) The aim of this study is to investigate the effect of two organophosphorous insecticides (Malathion and Chloropyrifos), and a member of the third generation insecticides that belong to the Insect Gross Regulators(IGRs), namely Dimilin (Diflubenzuren, DFB, or TH6040) on the larval stages of the housefly Musca domestica L. which is a chitin synthesis inhibitor replicated three times. Data showed that dimilin gave high larval and pupal mortality rates coupled with pronounced morphological abnormalities and deformations, which are displayed and in immature and adult stages as reduction of thorax and abdominal segments leading to a high rate of emergence inhibition in the adult stage. The high dosages of both organophosphorous insecticides gave 99% larval mortality, however, the recommended low doses gave mortality rates of Malathion and Chloropyrifos as (87% , 72%) and (84%,78%), respectively. Statistical analysis of data(ANOVA) and Latin square showed no significant differences between replicates for the house fly population due to the stability of larval mortality for all applied dosages. https://www.biotech-asia.org/vol7no2/evaluation-of-two-conventional-insecticides-and-a-chitin-synthesis-inhibitor-against-immature-stages-of-the-house-fly-musca-domestica-l-diptera-muscidaeevaluation-of-two-conventional-insecticides/ Malathion; Cloropyrifos; insecticides; Dimilin (Difluobenzuron DFB); house fly