Why did the caterpillar cross the road?

Last week we went for a drive and in one area the white-lined sphinx caterpillars were crawling across the road. They weren’t in large numbers, but noticeable. Why were they doing that?

Adult white-lined sphinx

The caterpillars could have run out of food plants and were looking for another snack, but the more likely explanation was that they were in the “wandering phase.” When caterpillars have finished eating and growing, they may wander around looking for an ideal place to dig into the soil and pupate. Sometimes they wander onto roads, but they really do want to see what’s on the other side.

Have you seen any white-lined sphinx caterpillars or moths lately?