Do you mean frit fly or fruit fly?

check this paper

http://www.ctahr.hawaii.edu/haraa/documents/1991_EnvEntomolNematodepopulation.pdf

http://www.crec.ifas.ufl.edu/extension/diaprepes/bibliography/PDF/2JouEcoEnt934.pdf

http://ufdcimages.uflib.ufl.edu/UF/00/09/88/13/00027/00027.pdf

http://www.crec.ifas.ufl.edu/extension/diaprepes/bibliography/pdf/biocont383.pdf

http://scholar.google.pt/scholar?as_q=entomopathogenic+nematodes+to+control+fruit+flies&as_epq=&as_oq=&as_eq=&as_occt=any&as_sauthors=&as_publication=&as_ylo=&as_yhi=&btnG=&hl=en&as_sdt=0%2C5

if you couldn't open them tell me I can do it for you.

good luck

You can read this article

Dear Mahmoud Farag Mahmoud, Dr-Abdalbaset A. A. Bugila and Nabil El-Wakeil many thanks for your participation and answers

Best wishes from jawad