Garlic in Egypt is usually attacked in the field by T. tabaci Lindeman and D. antiqua Meigen. This work aims to investigate the population fluctuations of both insects on garlic crop under Fayoum governorate conditions as well as their chemical control using chlorpyriphos and fenitrothion insecticides. Data obtained revealed that the population of T. tabaci ranged 4 - 605 insects/10 plants, while that of D. antiqua ranged 1.3 - 6.0 larvae/100 plant. The highest infestation percentage with D. antiqua was 9.3 and 11.4% in 2008/2009 and 2009/2010 seasons. Chemical treatment for both insect pests with chlorpyriphos and fenitrothion gave a good control over 90% in the two seasons.