This book introduces transcriptomics and presents an array of its uses in entomology, past and present. It starts with a thorough introduction to how transcriptomics works, its history, and some of its broad-stroke uses in insect science (Chapter 1). This chapter is followed by an exhaustively comprehensive look at how transcriptomics analysis is performed, and the software packages available to help one go from next-generation sequencing data to an interpretable dataset (Chapter 2). It continues with reviews of how transcriptomics has been used within larger subfields of entomology, showing different applications of the basic techniques covered. Transcriptomics and other next-generation sequencing technologies are ushering in radical new ways to approach pest management by finding new... targets for control, genes responsible for pesticide resistance, and even novel pathogens (Chapter 3). This is exemplified by the many studies done on the aphids, often with non-model but economically significant species for whom genomic data does not exist, which have succeeded in finding critical genes involved in aphid-plant interactions and host specificity and finding targets for biocontrol by blocking transcription of key genes (Chapter 4). Identifying new pathogens has been particularly important for honey bees ( Apis mellifera ), where transcriptomics revealed several new pathogens with potential links to Colony Collapse Disorder (Chapter 5). Discoveries within insects can have implications throughout biology: researchers use transcriptomics to accelerate the discovery of certain large yet conserved gene families, such as the hyper-diverse and multifunctional cytochrome P450s of interest to toxicologists, physiologists, agriculturalists, pharmacologists, and more (Chapter 6). The book ends with case studies going into more depth on how transcriptomics has been used to reveal more specific facets of a particular system. The cases presented include untangling insect-microbe interactions in cryptic parasitoid wasps ( Megastigmus spermotrophus ) (Chapter 7), identifying conserved insect digestive enzymes from the silverfish ( Ctenolepisma longicaudata ) transcriptome (Chapter 8), discovering the function of mysterious organs in the stick insects (Phasmatodea) (Chapter 9), and using functional transcriptomics to describe the chemical defenses of the bombardier beetle ( Brachinus elongatulus ) (Chapter 10).