Machani MG, et al. - Researchers investigated the influence of blood meal and mosquito age on pyrethroid tolerance in field-collected Anopheles gambiae from western Kenya. Alongside the pyrethroid-susceptible Kisumu strain, they reared wild mosquito larvae to adulthood. Deltamethrin resistance was monitored in adult females from the two populations when they were young at 2–5 days old and older 14–16 days old and whether fed or unfed for each age group. The predominant species was Anopheles gambiae sensu stricto comprising 96% of specimens and Anopheles arabiensis comprised 2.75%. As per results, mosquito age and blood feeding status were correlated with increased tolerance to insecticides as blood feeding may be playing an important role in the toxicity of deltamethrin, allowing mosquitoes to rest on insecticide-treated materials despite treatment. Findings seem to be valuable for the sustained effectiveness of the indoor residual spraying and insecticide-treated nets based control programmes that target indoor resting female mosquitoes of various gonotrophic status.