Prepatterning ofPapilio xuthuscaterpillar camouflage is controlled by three homeobox genes:clawless,abdominal-A, andAbdominal-B
Color patterns often function as camouflage to protect insects from predators. In most swallowtail butterflies, younger larvae mimic bird droppings but change their pattern to mimic their host plants during their final molt. This pattern change is determined during the early fourth instar by juvenile hormone (JH-sensitive period), but it remains unclear how the prepatterning process is controlled. UsingPapilio xuthuslarvae, we performed transcriptome comparisons to identify three camouflage pattern–associated homeobox genes [clawless,abdominal-A, andAbdominal-B(Abd-B)] that are up-regulated during the JH-sensitive period in a region-specific manner. Electroporation-mediated knockdown of each gene at the third instar caused loss or change of original fifth instar patterns, but not the fourth instar mimetic pattern, and knockdown ofAbd-Bafter the JH-sensitive period had no effect on fifth instar patterns. These results indicate the role of these genes during the JH-sensitive period and in the control of the prepatterning gene network.