Collection of ecological data such as the temporo-spatial distribution of a species is very difficult, due to broad distribution over large areas, phenology, and lack of resources for field survey. Citizen science, which is a cooperative scientific endeavor between researchers and interested citizens, is ideal for collecting large-scale ecological data. However, lack of proper equipment, species identification, and/or communication between researchers and participants are hindrance for a successful citizen science project. Here, we introduce the concept and methods of large-scale ecological data collection using smartphone apps. Most of the ecological data typically consist of sound or video recording, picture, geographic coordinate, and notes. There are several apps that can collect some or all of these ecological data. Furthermore, the result of a survey can be reported to researchers using Google Docs. The data collected by non-specialists can be validated by cross-checking of the survey report by Google Docs and the ecological data sent by apps. Finally, we report the results of a citizen science project in which temporo-spatial distributions of cicada species in Korea were studied via smartphone apps and Google Docs.