Insecticidal effect of deet on mosquitoes. a) Mortality rate among A. aegypti exposed for 1 h to paper impregnated with deet in World Health Organisation bioassays. Doses applied on paper were compared with standard skin applications of commercially available formulations containing deet (lower and upper deet formulation concentrations 5 to 100% were taken from the review of Xue et al. ). Deet formulation concentrations (%) were converted to doses (μg/cm2) based on 5 ml being the average volume required to cover a human arm . The figure showed that the doses used on skin (400 μg/cm2 to 8000 μg/cm2) were equivalent or greater than doses showing insecticidal properties in the case of close contact (LD50 = 830 ± 30 μg/cm2, s.e.m; LD95 = 1,180 ± 50 μg/cm2).