All of these species are found within Florida. Moths of this family have a medium to large body size with a wide wingspan. The cecropia moth, Hyalophora cecropia (Linnaeus), is the largest North American species of Saturniidae and has a wingspan up to six inches (15 cm). The adults in this family have mouthparts that are either very reduced or absent. They rely on resources that are acquired by the caterpillars (larvae). The caterpillars are robust and can exceed four inches (10 cm) in North America.
The buck moth is in the subfamily Hemileucinae, the buck and day moths. The individuals within this subfamily are found only in the Western Hemisphere. The majority of the species occur in the Neotropics, the region of the Western Hemisphere that occurs south of the Tropic of Cancer and includes southern Mexico, Central and South America, and the West Indies (Scoble 1995). Caterpillars in this subfamily have numerous multi-branched spines on their bodies, which are used defensively, delivering a sting when touched (Wagner 2005). The range caterpillar, Hemileuca olivae Cockerell, occurs in Mexico and in parts of the U.S. states of Colorado, Kansas, New Mexico, Oklahoma and Texas. This caterpillar is found on grasses and can be problematic for livestock in infested pastures (Opler et al. 2009b). The adult females of a Neotropical genus, Hylesia, also possess urticating (stinging) hairs on their abdomen. These hairs are used both as defense for the adult and to defend their eggs (Scoble 1995). The larvae of this genus possess stinging spines as well.
Larvae: According to Wagner (2005), the background color of the buck moth larvae is generally black; however, it can be almost white. The thorax (first three segments behind the head) and abdomen (segments behind the thorax) are heavily covered with white spots. The spiracles (openings to the respiratory system) have a pale brown color and are edged with black. The spines that the larva uses to defend itself are multi-branched and occur in multiple rows on the body. The spines found in the rows on the top of the body are longer and have more branches. The larvae can reach a length of 6.5 cm (2.5 inches) when they are fully grown.
Buck moth caterpillars that have a light background color can be confused with both the Nevada buck moth, Hemileuca nevadensis Stretch, and the New England buck moth, Hemileuca lucina Henry Edwards. The larvae of these three species can best be distinguished based on the preferred host plants (Wagner 2005). The caterpillars of the Nevada buck moth feed principally on willow, while those of the New England buck moth feed on meadowsweet, Spiraea spp. In addition, the spines of the buck moth are longer than those of the other two species (Ferguson 2005).
Like other members of their subfamily, buck moth larvae are gregarious (group together) for their first three larval instars (Wagner 2005). After the third instar, the larvae separate from each other and wander onto other plants where they feed until ready to pupate. The caterpillars pupate in debris that is either near to or on the ground, and if they spin a cocoon, it is not very large (Ferguson 1971). Buck moths may not emerge from their pupae for up to two years. Because the adults have no functional mouthparts they do not feed. Their main purpose is to mate and lay eggs.
The spines in the buck moth occur on raised, sclerotized (hardened) portions of the larva's cuticle that are known as tubercles and scoli. The spines found on these structures are associated with venom glands that occur within the caterpillar's body. According to Diaz (2005), the sting of the buck moth is similar to that of the saddleback caterpillar, Acharia stimulea (Clemens). The sting produces pain immediately, which then spreads to nearby lymphatic nodes. The caterpillar's sting then causes swelling and redness to occur. These symptoms can last for as little as a day to over a week. Wagner (2005) reported that the stings he received from a buck moth caterpillar were still present after ten days and the venom of the caterpillar caused a small hemorrhage where each spine had stung him. According to Diaz (2005), severe reactions to the venom of the buck moth (such as anaphylaxis) are rare. He recommends treating stings from these caterpillars by washing the site immediately in order to remove any loose spines that might be present. The site should be allowed to dry without the use of a towel. Any remaining spines should then be removed with an adhesive such as duct tape. Finally you can apply ice packs to the site to relieve some of the pain. Not handling caterpillars that have spines is one of the best ways to avoid receiving stings.
Authors: Clare Scott and Phillip E. Kaufman, University of Florida
Photographs: Lacy L. Hyche, Auburn University; Howell C. Curtis; James Castner, University of Florida; Gerald J. Lenhard; Ronald F. Billings, Texas Forest Service; Pennsylvania Department of Conservation and Natural Resources - Forestry Archive; David J. Moorhead, University of Georgia; and Susan Ellis
Graphic: Butterflies and Moths of North America
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-464
Publication Date: September 2009
Copyright 2009 University of Florida
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Department of Entomology and Nematology
Division of Plant Industry
Electronic Data Information Source
adult buck moth
adult luna moth
adult polyphemus moth
adult cecropia moth
polyphemus moth caterpillar
adult male buck moth
larva - dark form
larva - light form
eggs
larvae feeding
pupa
adults mating 
larval spines