This paper presents mosquito mapper: an android phone application created with the goal of giving science-driven citizens the means to monitor mosquito populations in an urban environment. Mosquito mapper allows the recording of mosquito encounters as well as conditions surrounding the encounter. It also features a rudimentary identification tool. The goal of the application is to create a database and construct a map of the encounters free to consult for citizens and scientists. Such database constitutes a necessary first step for the development of useful management strategies addressing potential human health threats induced by mosquitoes. The citizen scientist may voluntarily provide other additional information on the circumstances of the encounter that may contain scientifically useful information. We describe the current features of the application, showcase the limited data gathered so far, then discuss the strengths, limits, potential scientific value and suggest possible future extensions for the application. The original city for which the application was developed is Berlin, Germany, but the application is coded in such a way that it is easily applicable to any urban environment.

9This paper presents mosquito mapper: an android phone application created with the goal of giving 10 science-driven citizens the means to monitor mosquito populations in an urban environment. 11Mosquito mapper allows the recording of mosquito encounters as well as conditions surrounding 12 the encounter. It also features a rudimentary identification tool. The goal of the application is to 13 create a database and construct a map of the encounters free to consult for citizens and scientists. 14 Such database constitutes a necessary first step for the development of useful management 15 strategies addressing potential human health threats induced by mosquitoes. The citizen scientist 16 may voluntarily provide other additional information on the circumstances of the encounter that 17 may contain scientifically useful information. We describe the current features of the application, 18 discuss their strength, limits, potential scientific value and suggest possible future extensions. The 24 109 We decided to restrict ourselves to such a low level of identification because inner city Berlin is 110 mostly populated by mosquitoes of the genus Culex (Ann-Christin Honnen, pers.comm), to prevent 111 high level of inaccuracy from the user while remaining entertaining, and to avoid asking overly 112 5 complex morphological questions to untrained users (but see planned features). If the user has not 113 completed the "locate" activity, they are asked if they want to. 114 Questionnaire 115 After the "locate" activity, the user is asked to provide extra information regarding the context 116 within which the encounter took place. The set of answers given is sent together with the location 117 data (Figure 3). The questions were designed with the help of Ann-Christin Honnen from Swiss 118 Tropical and Public Health Institute, Basel, Switzerland. The set of answers from the questionnaire 119 will help determining the behaviour of the mosquito (e.g.: diurnal or nocturnal), their amount and 120 the likelihood of the encounter. They are complementary to the identification activity to determine 121 whether the encounter recorded took place with a mosquito. 122 Pictures 123At the end of the questionnaire, the user is asked to take a picture of the mosquito encountered. By 124 choosing yes, the phone camera opens. Ideally, the pictures taken by citizens could be used later 125 by zoologists as a way to improve species distribution maps although preliminary tests were 126 inconclusive. Pictures are usually large files, which could clutter our database. To reduce the size 127 of images, these are modified locally using a BLOB (Binary Large Object) procedure. This 128 procedure transforms the bitmap image taken with the camera into a bytes array. The bytes array 129 is then sent directly to the server. Image quality is decreased to a quarter of the original picture.