The watermelon Citrullus lanatus contributes to food security. It production is dicreased by the attacks of Diaphania hyalinata. This study was carried out to evaluate the repellent effect of garlic (Allium sativum) and lemongrass (Cymbopogon citratus) on D. hyalinata in watermelon cultivation. The experimental setup was a Fisher block with four treatments. Insects were collected ten times, one observation per week, using the direct observation method. In the control plot, the attack rate on C. lanatus plants was 95.83%. The attack rate was lower on the C. lanatus plots than on plots associated with lemongrass (68.75%) than on plots associated with garlic plants (87.50%) and plots treated with Tihan 175 O-TEQ (83.33%). The plant attack intensity was type II on the plots with treatments and type III on the untreated plot (I = 35.42%). The highest fruit attack rate was recorded on the control plots. The C. lanatus fruit attack rates on plots with lemongrass (23.79%) or garlic plants (23.73%) and those treated with Tihan 175 O-TEQ (23.87%) were similar. Yield losses caused by D. hyalinata were higher on the control plot (66.49%) than on the C. lanatus plots associated with lemongrass (23.86%), garlic (22.17%) and Tihan 175 O-TEQ treatment (23.50%). The percentage reduction in attacked fruit compared with the untreated control was 75% for C. lanatus plots combined with lemongrass, 85% for plots combined with garlic and 75% for plots treated with Tihan 175 O-TEQ. Plants of A. sativum and C. citratus intercropped with C. lanatus cultivation increased yields.