As a consequence of the development of insecticide resistance in Aedes aegypti, there is a need to find new molecules to control it. Bioactive peptides are considered promising natural products due to their broad spectrum of antimicrobial and insecticidal activity. Previous work has shown the potential of alpha-helix protein fragments as insecticides. In this work, using in silico prediction methods were designed peptides with oral insecticidal activity for Ae. aegypti larvae, from the design of analogs of the insecticidal peptide BTM-P1 and the search for other segments alpha-helix present in domain I of Cry and Cyt toxins from Bacillus thuringiensis. Three BTM-P1-like peptides and a 16 amino acid segment were found in the Cyt2Aa toxin, called CBYH3, with insecticidal potential and no or reduced hemolytic activity. Molecular dynamics also validated the toroidal pore formation mechanism of BTM-P1 on a simplified eukaryotic membrane model. The cellular damage caused by BTM-P1 and CBYH3 and their association to the mitochondria and peritrophic matrix was observed in the mosquito gut using the immunogold technique.