Current interventions targeting indoor malaria vectors, particularly the use of long-lasting insecticidal nets (LLINs) and indoor residual sprays (IRS), have been a cornerstone of the recent significant decline in malaria morbidity and mortality [
1]. As a result, malaria-related deaths have declined by more than half in sub-Saharan Africa between 2000 and 2015 [
1,
2]. The sustainability of these interventions is, however, threatened due to increased vector resistance to available insecticides [
3‐
5], and the change in mosquito biting behaviour to seeking blood meals outdoors [
6‐
8], with some populations shifting the time of biting activity from late night to early evening [
8‐
10]. These behavioural changes favour residual malaria transmission, presenting a major roadblock to further reduce malaria prevalence and enhance the sustainability of malaria vector control [
11]. Whilst the current strategy of IRS and ITN control has made great strides against malaria, the global number of malaria cases has not declined in the past few years, but rather has increased by 5 million over the course of a single year in 2016, with no reduction in mortality evident for the first time in a decade [
12]. Outdoor interventions directed against adult mosquitoes are lacking [
13], and an increased understanding of the ecology and behaviour of exophilic malaria vectors is needed to improve the sustainability of existing control strategies. In addition, this may further act as a guide for the deployment of appropriate outdoor monitoring and control tools [
14].
The sustainability of existing integrated vector management (IVM) tools should be actively maintained, and enhanced by the addition of novel interventions, particularly vector control strategies targeting adult anophelines outdoors [
13,
15]. Early studies by Gillies [
16,
17] revealed that endophilic
Anopheles gambiae sensu lato (s.l.), the primary malaria vector at this time, predominantly rested indoors, but with a small proportion of mosquitoes found to be resting in shady zones at some distance from human habitation. In the interim, changes in the biting patterns of several mosquito species have arisen, whereby a far greater proportion of female
Anopheles species are found to both feed and rest outdoors [
6‐
10]. Additionally, the habitat has undergone considerable changes, populations of humans are denser, and the agricultural environment is more intensely farmed with greater use of irrigation [
18]. In view of the known changes in mosquito feeding behaviour and the habitat, few recent studies describing the outdoor behaviour of mosquitoes have been conducted [
19], which may be partly due to the large effort required to catch mosquitoes outdoors as opposed to indoors [
20]. Existing knowledge builds extensively on the foundation of the work of Gillies [
16] who studied the resting site selection of
An. gambiae s.l. and
Anopheles funestus in natural and artificial resting sites. More recent studies in
Anopheles mosquitoes show that these mosquitoes choose outdoor resting micro-habitats based on several different environmental factors within the landscape at a fine spatial scale [
21]. Moreover, a number of studies have associated landscape characters with the distribution or aggregation of exophilic mosquitoes [
22‐
24]. These studies have indicated that different physical and biological components of the environment are important factors affecting mosquito ecology, with habitat type [
22], land cover [
23], shade [
24], microclimate [
21] and the availability of blood meal hosts [
22] being positively associated with the adult distribution of exophilic mosquito species.
Outdoor monitoring and control tools can be used alone, or to augment other IVM strategies, to alleviate the malaria burden. It is, however, essential to fully understand the behaviour of exophilic populations to make the best use of both existing and novel tools. This study was conducted to explore the resting habitat selection behaviour of Anopheles mosquitoes outdoors and identify landscape characteristics associated with the resting sites which can later be used to optimize the positioning of traps in the landscape around human habitations.