The leaf miners, Liriomyza trifolii (Burgess) and L. bryoniae (Kaltenbch), (Diptera: Agromyzidae) are of the major pests that attack faba bean (Vicia faba) in Egypt. The incidence of diapause in larval-pupal parasitoids of these pests was studied by large-scale field samplings of their mature larvae and puparia, which were reared under natural outdoor conditions. The population size of L. trifolii was greater than those of L.bryoniae. Four larval-pupal parasitoids; Pseudopzomachus masii Nixon and Opius basalis Fischer (Braconidae), Halticoptera circulus (Walker) and Halticoptera sp. (Eulophidae) were recorded from the puparia of both leaf miner species between 2012 - 2015 seasons. P. masii was the most predominant parasitoid species in the seasons of study. The onset of pupal diapause was found among paper of the 1st sample, during the favorable weather conditions in the host insect until last collected samples 2 weeks before harvest. So, the diapause in Liriomyza spp. seems to be genetically programmed. Two types of diapause were observed during the season: firstly, a facultative winter diapause of 7-8 months, and secondly, a longer winter diapause of 11-21 months. The diapause intensity was highly variable depended upon the time in the season and the Liriomyza species. It appears that the diapaused wasps were able to maintain close developmental synchrony with the proportion of non-parasitized host puparia. This is the first report of diapause in Liriomyza spp. attacking faba bean plants and their larval-pupal parasitoids from the northern region of Egypt.
