(Merriam, KS (Kansas City area) This is a reddish colored caterpillar with a lighter pink (or reddish)stripe lengthwise down the top center of it’s back with what appears to be a split tail. It’s approx. 1 inch in length. The bottom of the caterpillar is green in color. There look to be very small spots along the side of it towards the bottom.I have found several of these in the past 2 weeks in and around my garage. We have lived here 12 years & I have never seen them before.
I believe your caterpillar is the mottled prominent. They turn pink as they get ready to pupate. And as they go into the later stages of being a caterpillar the tail gets shorter.
Theses are found in eastern North America…west to a line from TX to Manitoba.
The caterpillars feed on foliage of oaks as well as a few other deciduous trees like maple and beech. There is one generation in the north, two in the south.