The effect of vegetable diets on the larval development of two daytime butterflies in captivity at the Allpahuayo Research Center of the Instituto de Investigaciones de la Amazonía Peruana (IIAP), Iquitos, Peru, was determined. To evaluate their biological cycles, 20 freshly emerged larvae of each species were used individually and, to estimate the effect of different diets in their larval development, a completely randomized design was used with two treatments and different replicates (n1 = 31 and n2 = 14). It was reported that the diet with the host plant Arachis pintoi was optimal for both Morpho menelaus occidentalis and Morpho helenor theodorus species, which completed their biological cycles in, 97.51±7.98 days (n = 15), with 75% survival, and 73.22±7.26 days (n = 14), with a survival rate of 70% respectively. Morpho helenor theodorus completed its biological cycle on its natural host plant Platymiscium stipulare in 75.84±10.19 days (n = 10), being its biological cycle longer with a lower survival rate (50%). The host plants Vigna aff. candida and Desmodium adscendens were not adequate for the two species of Morpho, since the larvae died in the first stage. In Morpho helenor theodorus, there is no relationship between gender and diet in relation to longevity (Chi square test). Females lived in average 53.76 days and males 25.45 days.