Range of RNAi phenotypes categorized into three classes. Class ‘H’ embryos displayed head only or head plus posteriorly undifferentiated tissue, only found in Pa-cadRNAi. Class ‘T’ embryos form the head and some thoracic segments properly, but are truncated after either T2 or T3; this was the most common Pa-cadRNAi and Pa-Wnt1RNAi phenotype. Class ‘A’ embryos were observed in both Pa-cadRNAi and Pa-Wnt1RNAi. These embryos developed complete head and thorax with defects in abdominal segmentation, usually tapering at the posterior. Control Pa-H2O embryos were wild type in appearance.