In this paper we propose a suite of index structures and algorithms which permit us to efficiently support querying of historical data in flash-equipped sensor devices. Our techniques are designed to consider the unique read, write and wear constraints of the flash memories; this combined with very limited data memory on sensor devices prohibits the direct application of most existing indexing methods. We have implemented our methods using nesC and have runextensive experiments in TOSSIM, the simulation environment of TinyOS. Our experimental evaluation using trace-driven real world data sets demonstrates the efficiency of our indexing algorithms.