Abstract: A method of introducing a molecule of interest into an insect or an insect cell includes interacting a cell-penetrating peptide with a molecule of interest to form a complex. The structure is then placed in contact with an insect or an insect cell and allowing uptake of the complex into the insect or insect cell. Alternatively, an RNA polynucleotide (mRNA, or an RNAi-mediating molecule) can be introduced in an insect or an insect cell by interacting a peptide with the polynucleotide of interest to form a complex, allowing uptake of the RNA complex into the insect or insect cell, and expressing the polynucleotide in the insect or an insect cell.