Pachylia syces is a moth of the family Sphingidae.

It is found from Mexico through Belize and Honduras to Brazil, Bolivia and Argentina.

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.