The aim of this work has been to determine the characteristics of seven natural peptide substances. The chemical formulas of the substances were as follows: HCL-TrypNH₂, AC-Ach-OH, Perm(C-7)-α-Ala-AN, Boc-Ala-AN, H-Tyr(O-C₁₀-H₂₁)OH, , C-t-Per-An. The experiment was executed on five species of storage pests: Tribolium confusum Duv., Stiphilus granarius L., Stegobium paniceum L., Trogoderma granarium Ev., Rhizopertha dominica F. The experiment consisted of two parts. In the first part, the deterrent effect of the peptide substances was assessed by saturating the food (wheat wafers) to 1% concentration of each substance. The second part involved testing the effect of the substances on mortality of pests. The development of insects was screened for 30 days. The deterrent effect of the substances applied varied and was dependent on a species of pests. It was found out that substances of II and III deterrence class were effective in protecting stored products from Tribolium confusum and Sitophilus granarius. All the substances tested in the course of our study can be applied against Stegobium paniceum. The other two pests were neither deterred nor was their mortality affected by any of the peptide substances examined.