Invading Horned Devils: Giant Hickory Emerges in Southern States Forests

In a study developed by researchers from the University of Florida, the regal or royal walnut moth, Citheronia regalis (Fabricius), is one of our largest and most spectacular moths. Like most other moths, it is nocturnal but can be seen at night. The imposing larva, known as the hickory horned devil, is most often seen when it is fully grown and emerges from the trees in search of a pupation site.

The Alabama Wildlife and Freshwater Fisheries Division shared photos of an "impressive" hickory horned devil discovered by a public member in Jefferson County. According to the Missouri Department of Conservation, the caterpillars are the larvae of the regal moth, Citheronia regalis, one of the country's largest flying insects with a wingspan of up to six inches.

The regal moth can be found throughout the eastern United States, from New Jersey to Missouri and south to eastern Texas and central Florida. The southern half of its range is more common. It was previously found north of Massachusetts and appeared to be declining elsewhere in its rangedue to increased pesticide use.

Crawling History of Hickory Horned Caterpillar

It is about the size of a large hotdog and ranges from 12.5 to 14 cm. The caterpillars' colors vary, but they are typically blue and green. The second and third thoracic segments contain two long and shorter orange, black-tipped scales. Each abdomen segment has four short, black scales, and segments 2-8 have a pale, oblique lateral stripe. The larva, despite its intimidating appearance, is completely harmless. In the southeastern United States, the caterpillar primarily feeds on walnut, persimmon, and hickory trees.

Don't be alarmed if you find a caterpillar in your tree-completely it's harmless.

In the Facebook post, Alabama Wildlife and Freshwater Fisheries Division said that the best time of year to look for them is between July and October. The caterpillars eat continuously before crawling down from the trees to pupate in the soil. Adult moths spend the winter in the soil, emerging in early summer after their wings have hardened.

From a Horned Devil to Spectacular Silkmoth

The hickory horned devil caterpillar is a giant silkworm moth species. This bug cannot eat because it lacks functional mouthparts, but it can live for about a week before succumbing to exhaustion. The larvae of the regal moth are a beautiful and fascinating member of the native fauna that should not be killed. If a larva crawls on pavement or in dense turf grass where it will have difficulty burrowing, it should be relocated to a soft soil or mulched area where it can burrow for pupation. The wingspan of the regal moth ranges from 9.5 to 15.5 cm. Males are bigger than females. Gray to gray-green forewings with orange veins and a row of seven to nine yellow spots near the distal margin. There are also isolated yellow discal and basal spots on its wings. The hind wing is mostly orange, with a yellow spot at the base and yellow patches (or spots) on the coastal and anal margins. One to two rows of gray-green spots may also appear on the hind wing. The body is orange with a narrow yellow band running through it.

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