Pachylia syces is a moth of the family Sphingidae. It is found from Mexico through Belize and Honduras to Brazil, Bolivia and Argentina. It is also found on Jamaica. There is a pale median band on the forewing upperside which is separated into two patches. Occasionally the patches are connected into a continuous transverse band, but if so, the band so formed is strongly constricted. The hindwing upperside is almost unicolorous, darkened distally, without distinct bands and with a conspicuous white tip. There are probably multiple generations per year.