Five-spotted Hawkmoth, Manduca quinquemaculata (Hodges # 7776), Fermilab, DuPage County, Illinois, 12 September 2006
This species is very closely related to the Carolina Sphinx. The caterpillar of the Five-spotted Hawkmoth is called the tomato hornworm.
However, my experience is that most of our common "tomato worms" here in the Chicago area are actually the "tobacco hornworm", Carolina Sphinx caterpillars.
The moth sitting on my hand illustrated the size scale. As is typical for this species, it was quite large.