-

The presents study was carried out on the biology of Phytomyza orobanchiaeduring 1995 - 1996. The flies overwinter as pupae in remains of Orobanche spp. Fertilised females lay eggs in flowers and stalks of Orobanche
spp. Eggs are inserted singly. This insect has 4 generations per year in Urmia. Under field conditions the insect damages 43.5 +- 9.46 of the seed capsules of
Orobanche spp. The preoviposition, oviposition and postoviposition periods at lab. conditions averaged 3.15 + 0.42 , 5.16 :!: 0.12 & 2.6:!: 0.18 days
respectively. The average number of eggs per female was 34.8+ 4 eggs. This insect has three larval ins tars at 26 + 10 c and 65 :!: 5 RH. The pupal stage under same conditions lasted 10. 1 + 0.2 days for males, and 9.5 :!: 0.3 days for females. Average longevity for both male and female was 6.8 :!: 0.69 and 10.6+0.95 days respectively. The larvae pupate in stems and capsules of host plants. The developmental time of generation lasts 27.9 + 3.25 days. Results
revealed that 45% of Orobanchecapsules were infested with 1-3 larva or pupa.