The current study was carried out to investigate the effect of stored grains infestation with S. granarius and storage periods on detection of toxicants secretion as benzoquinones. The results showed that loss of wheat grains significantly increased with increasing storage periods and different insect densities. The highest losses percentagecaused byS. granarius was 6.95 % at densities of 20 pairs. The results showed there is only Ethyl 1,4-benzoquinone was the toxic compound detected in all insect densities and storage periods. The benzoquinones secreted by S. granarius adults increased with an increase of the S. granarius density. The highest values were recorded 313.9 and 394.78 ± 9.33 µg/g wheat flour with the highest insect density (20 pairs) at 2 and 4 storage periods resp. Also reported results, the concentration values of ethyl 1,4 benzoquinone per insect were 0.55 ± 0.04 and 0.35±0.03 µg/g wheat flour with the highest insect density (20 p) at 2 and 4 storage, resp. We can confirm that the organic compound ethyl 1,4 benzoquinone was coming from S. granarius as defensive secretions.