Through the PCR diagnostic technique, it found the Daisenura oleae, from the Cecidomyiidae family and the order Diptera. Olive leaf flay were characterized by their activity and continued presence during the activity season. The results of the electrophoresis of flys DNA, which was extracted from olive leaf adults. Obtained pure DNA, and the purity of the parasite DNA was confirmed by a successful operation. Electrophoresis using Agarose gel and showing the nucleic acid bundles clearly. The sequence of the nitrogenous bases of the samples (Cyanobacteria) that were under investigation was determined, as products were sent for PCR representation, and the sequence reading of the genes was completed by depending on the 3130 genetic analyzer that was equipped from the Japanese company Hitachi. BLAST software was used to compare the gene sequences that were sequenced with the gene sequences that were documented in the National Center for Biotechnology Information (NCBI). The findings of this comparison were then analysed. The products of the amplified packages resulting from the PCR reaction were sent outside Iraq to study the sequence and sequence of the nitrogenous bases and compare them with the original cytochrome c oxidase subunit I (cox1) gene stored in the Global Genome Bank with specific sites of the gene to be studied, and it was found that there are sites of variation or variation in the nucleotide sequence compared to with the original gene at the NCBI website, and the isolate match was 100%. The isolate was recorded in the Gen Bank with accession number LC757225.1, and the genetic tree was drawn to find out the relationship between the Iraqi insect isolate and the rest of the insect isolates, and the closest was the American isolate.