Butterflies and moths go through four stages in their life cycle – egg, several larvae or caterpillar phases (called instars), pupae and adult. Sphinx moth Pachysphinx occidentalis) caterpillars are beginning to burrow underground where they will pupate in shallow burrows before eventually metamorphosing into adults.
I previously posted pictures of an adult sphinx moth, also commonly called a hawk moth or a big poplar moth. The light green sphinx moth caterpillar is about six inches long and as much as an inch in diameter. It is big! White lateral stripes are visible on its back.
This specimen is in its last instar (larval stage) as evidenced by the short caudal (at or near the tail or posterior end) horn. When I saw this caterpillar it was burrowing into the ground near our house (Modoc County CA). I disturbed it long enough to quickly take pictures, then watched as it continued to create a shallow burrow in which to pupate.
Our yard is a perfect environment for sphinx moths. The caterpillars ravenously eat poplars, cottonwoods and willows, all of which we have in abundance.
Perhaps next year I will see the beautiful sphinx moth into which this caterpillar “morphs”.