The objective of the current study was to identification and evaluate the essential oils “Eos." of cotton and tomato plants to determine the responsive attraction of some pests; Spodoptera littoralis (Boisd.),  Pectinophora gossypilla (Sound.) and Earias insulana (Boisd.) which caused a lot of damage to cotton and vegetable crops in Egypt. An experiment of two choice olfactometer systems was used in moths' bioassay to study the effect of which part of cotton plant and three tomato varieties can attract or repellent of volatile oils EOs. Essential oils of cotton and tomato plants were extracted and chemically identified by Gas Chromatography/Mass Spectrometry (GC/MS). Eighty-six volatile compounds were identified from leaves, bolls and flowers of cotton representing (99.45, 99.57 and 99.02%) from total mass, respectively. The major constituent of their chemical composition was Caryophyllene (17.83, 22.01 and 24.63 % for cotton leaves, flowers and bolls, respectively), D-Limonene recorded the largest compound in tomato varieties (“Real Madrid" 20.35 %, “Bs" 10.49 % and “Alissa" 12.07 %). Laboratory bioassay of the target pest “female and male moths" of P. gossypilla, obtained that the highest total response were83.09, 64.0 and 57.0 % for cotton leaves, flowers and bolls oil. E. insulana was the highest attracted moths to cotton bolls (64.91 %.), while S. littoralis estimated a positive response to cotton leaves (76.6 %). The present results may providea new strategy in the future to use plant essential oils as amixture baited on pheromone traps to attract and kill those pests.