Medical entomology involves the study of medically important insects, such as cockroaches and mosquitoes, which have a dangerous role as transmitters for deadly diseases, such as Malaria, Leishmaniasis, and Dengue fever, which are responsible for many deaths among humans. Huge concern about the use of chemicals insecticides encourages the development of alternative methods for insect control, and due to the harmful effects of these chemicals, new strategies are being developed to replace or reduce the use of synthesized insecticides. Therefore, chitinolytic enzymes produced by microorganisms have a significant effect as biocontrol agents and will be more critical than synthetic pesticides for control. This study was primarily aimed to study the impact of various isolated bacteria using chitinolytic and spraying assays against adult stages of Periplaneta americana and Aedes aegypti as biological controls. Eight species of bacteria were isolated, and only Chryseomonas luteola was used against adult insects because of its high chitinolytic activity by spraying assay. Our results showed that the LC₅₀ values of C. luteola against P. americana were 22.04% and 17.21% after 24 and 48 h, respectively. For A. aegypti adult stages, LC₅₀ values of C. luteola were 2.78% and 2.12% after 24 and 48 h, respectively. Based on the results of this investigation, it is reasonable to say that using microbial insecticides may be an effective strategy to control the adult stages of P. americana and A. aegypti.