We got this photo from Rock Hoppin’ yesterday and thought that make a nice addition to our Animals&Critters of St. John section. It is a Frangipani Caterpillar that will eventually turn into a giant moth, a common moth in the American tropics and subtropics in lowland habitats.

Female moths lay 50 to 100 eggs in clusters on leaves of host plants that include frangipani, other members of the dogbane family, and rubber vine. Each egg is ellipsoidal in shape, pale green in color, and not sculptured except for minute punctures on its surface.

Once the eggs hatch, the caterpillars begin eating. The caterpillars often appear in gardens or landscaping and can defoliate frangipani trees in a few days or couple of weeks. One caterpillar can devour three large leaves per day. They typically start feeding from the leaf tip and have been known to feed on tree stems if leaves are unavailable.

Frangipani Caterpillar on St. John

The frangipani caterpillar featured in this article was spotted by Captain Steve of Rockhoppin’ Charters in their boat yard.

The caterpillar’s color pattern is a warning sign to predators that they are toxic. Some of the caterpillar’s host plants produce white, toxic latex that the frangipani caterpillars are able to detoxify and use for defense purposes. Most potential predators avoid eating these caterpillars since they taste bad due to the toxic plants they eat. The frangipani caterpillar is considered a coral snake mimic in Costa Rica. They wave their heads back and forth like snakes when disturbed, and they bite when handled so don’t pick them up with your bare hands

Frangipani Caterpillar Video

A video posted by Arley Jack (@highjackphotography) on Dec 18, 2015 at 5:05am PST

Frangipani Moth

The Caterpillar will eventually molt to the pupal stage. A newly formed pupa is yellow. After 2-3 hours, brown spots appear on the surface. Coloration eventually darkens to a yellowish-brown with lateral dark stripes on the thorax and rings on the abdomen.

An adult frangipani moth has brownish forewings, each with a dark spot and blurry gray and white markings. Its dorsal hind wings are dark brown with white markings along the inner margin and the lower half of the outer margin. The body is striped with transverse grey-white bands and wider black bands. The wingspan averages 12.7 to 14 cm. Female moths are typically larger than males and lighter in color.