respiration larval respiration A pair of air sacs of unknown function is present near the junction of thorax and abdomen in certain species. IDOMAL:0002149 IDOMAL:0002149 Larvae use an open respiratory system which impose limitations to the requirement for access to atmospheric oxygen. The mosquito larval tracheal system consist of two wide dorsal longitydinal trunks, two narrower lateral, and branches which run from them to all regions of the body. idomal_namespace