Technical Abstract: Our aim in this chapter is to provide an overview of the profound knowledge accumulated in recent years from invertebrate RNAi studies, but with a focus on agriculturally important arthropods. We start with a brief discussion of the RNAi mechanism to introduce readers to key concepts that underlie the practical application of RNAi discussed in the remainder of the chapter. Our discussion will include a number of important issues, including bidirectional transport of silencing signals, processing of dsRNA, homology-driven mRNA degradation and subsequent gene silencing. We will examine examples of gene silencing in different arthropod systems to illustrate commonalities and differences found in their silencing machinery. Considering the huge economic impact honey bees have on crop production and particularly on pollination of specialty crops, a substantial part of this chapter will be dedicated to honey bee research. Our discussion will also focus on the successful use of RNAi strategy as a control method for agricultural pests, including the Western corn rootworm, and Colorado potato beetle. These studies will help to design simple and cost-effective practical applications for the introduction to agricultural systems and medicine.