Oral aspirators can be used to collect mosquitoes resting among vegetation. For example, Mani et al.(1991), in studies on
Japanese encephalitis in India, collected adult female Culex tritaeniorhynchus, Culex vishnuiand Culex pseudovishnuifrom in and around
cattle sheds in the hour after sunset and multiplied the average number
caught by the proportion parous to obtain a ‘dusk index’. When this inhibited a sharp increase after transplantation of rice seedlings, but the
dusk index remained high after biting counts had decreased to a low
level. This was due to the paucity of Culex tritaeniorhynchusat human
bait, and its abundance in dusk collections around cattle sheds. The dusk
index was therefore routinely used to monitor vector densities. Also in
southern India, Arunachalam et al. (2004) collected 150 454 female mosquitoes representing 6 anopheline and 12 culicine species using oral aspiative difficulty in locating natural outdoor resting sites and the dispersed
distribution of resting mosquitoes, alternative methods to oral aspiration
of individual mosquitoes are more frequently employed.