## 1 Introduction  
The Asian citrus psyllid, _Diaphorina citri_ Kuwayama, is the vector of the causal agent of the pathogens causing huanglongbing (HLB). HLB is the most damaging disease of citrus worldwide. HLB, also known as citrus greening disease, causes yellowing of shoots, stem dieback, sour fruit, crop losses and eventually tree death [1; 2]. The causal agent of this disease in the USA is presumed to be the bacterium, _Candidatus Liberibacter asitaticus_ (CLas) [3], and is transmitted from plant to plant through the movement and feeding of adult _D. citri_[4]. Found for the first time in 1998 [5], _D. citri_ has now spread throughout Florida and has been impossible to eradicate. The impacts of HLB on the Florida economy are dramatic. Approximately 80% of citrus is now infected with the pathogen [6] and the 2015-2016 citrus yield in Florida decreased by approximately 30% compared to the previous year, and is the worst season for this citrus industry in 50 years.  
Current methods to prevent the spread of HLB rely heavily on management of the psyllid vector. Typically, insecticides are used to manage populations of _D. citri_[7; 8], which has led to insecticide resistance [9] and negative impacts on populations of natural enemies [10]. While resistance to insecticides can be managed by rotation of modes of action through time and space [11], these chemicals often have undesired non-target effects and their use is limited by application restrictions to food crops [12]. Additionally, there are few options available to organic citrus growers to manage _D. citri_. Therefore, alternative pest control tools will be valuable for supplementing existing insecticide-based management programs. Pest control using botanical oils to affect insect behavior can be complementary to insecticide use, because the oils should not interfere with the insecticide mode of action. Botanical oils can disrupt host insect interactions by repelling insects from a host, deterring feeding, or by causing contact toxicity [13]. In addition, botanical oils are considered safe for many food crops and are often acceptable in organic farming, making them a versatile pest management option when traditional insecticides are not acceptable [13].  
Botanical oils have been evaluated as potential repellents for several insect orders including: Lepidoptera [14], Diptera [15], and Coleoptera [16]. For _D. citri_, a number of botanical oils have been evaluated in laboratory assays, including those from tea tree, thyme, lavender, rose, and coriander [17]. While some of those oils showed promising results in laboratory bioassays, the costs of the active ingredients prohibited development of formulations for use in the field [17].  
In this investigation, we evaluate previously untested botanical oils for behavioral activity (repellency) against _D. citri_ in the laboratory. Based on these results, we then only tested the most active oil under field conditions as a possible management tool for this pest. Fir, litesa, and citronella oils were chosen because they are widely available, considered inexpensive, and from non-Rutaceae plants (non-hosts). Our objectives were to: (1) test these oils for repellency to _D. citri_ in laboratory olfactometer bioassays; (2) determine if behaviorally active oil(s) deter settling of _D. citri_ onto seedling citrus in caged settling experiments; and (3) test oil(s) that were effective in laboratory experiments under field growing conditions. Given that fir oil was the only treatment to cause repellency of _D. citri_ in olfactometer bioassays (see Results), this was the only oil investigated further in settling and field experiments.