Two field experiments were carried out at Shandaweel Agricultural Research Station, Sohag Governorate, Upper Egypt during 2004/2005 and 2005/2006 seasons to study the effect of some agricultural practices i.e., distance between rows (60, 70 and 80 cm), sowing on one or two ridges and distance between hills (20, 25 and 30 cm) on the infestation of broad bean with the leafminer, Liriomyza trifolii (Burgess), and also to study the effect of 4 sowing dates (15th Oct., 30th Oct., 15th Nov. and 30th Nov.) on the infestation with the cowpea aphid, Aphis craccivora (Koch), the cotton whitefly, Bemisia tabaci (Genn.), jassids, Empoasca spp. and the leafminer, L. trifolii as well as the yield loss due to these insect pests. The obtained data showed that distance between rows (80 cm), sowing on one side of the ridge and distance between hills (30 cm), each alone recorded the lowest numbers of L. trifolii larvae during both seasons. Also, interactions of distance between rows (80 cm), sowing on one side of the ridge and distance between hills (30, 25 and 20 cm), as well as distance between rows (80 cm), sowing on two sides of the ridges and distance between hills (30 cm) also recorded the lowest densities of L. trifolii larvae during both seasons. The population density of A. craccivora and L. trifolii was significantly affected by sowing date. Sowing broad bean on 15th Oct. showed least infestation levels during both seasons. Highly significant positive correlation between total numbers of 4 insect pests and yield loss during 2004/2005 season (r = 0.981) and 2005/2006 season (r = 0.993) was observed. The highest yield loss (39.56 and 34.28%) was obtained in case of sowing date 30th Nov. during both seasons of study