This fierce-looking caterpillar is the immature stage of the Regal Moth (also known as the Royal Walnut Moth) - an attractive "giant silkworm" moth with a 5 - 6 inch wingspan. Full grown larvae vary slightly in color but are usually a bright bluish-green with orange thoracic horns, and can reach a length of 4 - 5 inches (roughly the size of a large hot dog!) This is one of our largest caterpillars and certainly one of our most frightful looking - although it is totally harmless. The spines are not poisonous and are not particularly sharp.

The caterpillars are usually found on pecan, hickory or walnut leaves, but do feed on a number of other trees, as well, and are present from July to October. Larvae mature in late summer to early fall, wandering around searching for a suitable place to burrow underground to pupate - usually in soft soil or compost. Overwintering occurs in the pupal stage. Although caterpillars of various sizes are present for a number of months, they are usually not noticed until they crawl down from their host tree when they are ready to begin searching for a pupation site.

Although larvae may eat a prodigous amount of leaf material, they are rarely abundant enough to be of any economic impact.

- by Dr. Cecil Smith, Associate Curator and Collection Manager - Arthropods Collection

Update: since the caterpillar has arrived at the Museum, it has undergone a change and pupated (see left.) The pupation is expected to last until early summer, when the mature moth will emerge, but it has been noted that in some cases, pupation may last an additional year. We'll keep you posted.