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The aim of this work was to develop processing methods that safeguard the quality and antimicrobial properties of <i>H. illucens</i> and <i>B. mori</i> oils. We adopted a vegetable diet for both insects: leftover vegetables and fruit for <i>H. illucens</i> and mulberry leaves for <i>B. mori</i>. First, alternative techniques to obtain a good oil extraction yield from the dried biomass of <i>H. illucens</i> larvae were tested. Traditional pressing resulted to be the best system to maximize the oil yield and it was successfully applied to <i>B. mori</i> pupae. Oil quality resulted comparable to that obtained with other extraction methods described in the literature. In the case of <i>B. mori</i> pupae, different treatments and preservation periods were investigated to evaluate their influence on the oil composition and quality. Interestingly, agar diffusion assays demonstrated the sensitivity of Gram-positive <i>Bacillus subtilis</i> and <i>Staphylococcus aureus</i> to <i>H. illucens</i> and <i>B. mori</i> derived oils, whereas the growth of Gram-negative <i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i> was not affected. This study confirms that fat and other active compounds of the oil extracted by hot pressing could represent effective antimicrobials against bacteria, a relevant result if we consider that they are by-products of the protein extraction process in the feed industry.