Manual annotation of circadian genes
We further manually annotated well-studied circadian genes:period (PER), timeless (TIM), Clock (CLK),cycle (CYC) and cryptochrome (CRY), using BLAST v2.2.31 (Altschul, Gish, Miller, Myers, & Lipman, 1990). Reference protein sequences of insect circadian genes were obtained from the Uniprot database. Conserved domains within proteins were annotated against the conserved domain database (Lu et al., 2020). Circadian genes of the other 15 insect species were annotated in the same way. For a common domain of three genes (CLK, PER and CYC), a neighbor-joining tree was constructed using MEGA7 (Kumar, Stecher, & Tamura, 2016) with 500 bootstrap replicates.