In this study, we cloned full-length EcR cDNAs from the small brown planthopper Laodelphgax striatellus, the brown planthopper Nilaparvata lugens and the white back planthopper Sogatella furciferas. This is the first reporting of EcRs from either L. striatellus or S. furciferas. The deduced amino acid sequences of the EcRs show high levels of similarity to each other. The highest transcriptional level of the EcR gene was detected in the mid-fifth instar nymphs of N. lugens. Silencing of EcR expression by in vivo RNAi generated phenotypic defects in molting and resulted in lethality in most of the treated nymphs. Intriguingly, apparent wing defects in morphogenesis and melanization occurred during EcR knockdown in L. striatellus nymphs.