Avoidance/Control. Always wear protective clothing such as gloves and a long-sleeved shirt when working in areas heavily infested with puss caterpillars. During periods of _M. opercularis_ abundance, children should be instructed to stay away from infested trees and shrubs and not to handle caterpillars. If necessary, heavy puss caterpillar infestations may be treated with an appropriate insecticide. Envenomization Reaction/Treatment. (See appendix.) c. SADDLEBACK CATERPILLAR (_Sibine stimulea_) [Illustration: (unlabelled)] Identification. The saddleback caterpillar is easy to recognize since its brown sluglike body is covered mid-dorsally with markings that resemble a brown or purplish saddle sitting on a green and white saddle blanket. Upon close examination, stout spines can be observed along the caterpillar’s lateral body margin and on its four tubercles. Many of these spines are hairs that are connected at their bases with individual poison glands. Just prior to pupation and subsequent development into a moth, the caterpillar is 2-3 cm (0.8-1.2 in) long. Distribution. In general, the saddleback caterpillar in the United States is distributed southeast of a diagonal line drawn from Massachusetts through the middle of Texas.[68] Biology/Behavior. From May to November, _Sibine stimulea_ caterpillars may be found feeding on the leaves of a large variety of trees, shrubs, and other plants. Envenomization usually occurs when the victim accidentally contacts vegetation infested with these caterpillars. At the instant the victim’s skin contacts the caterpillar, the spine tips break off, thus allowing toxin to flow out of the hollow spines and into or onto the skin. Avoidance/Control. When working in infested areas, wear gloves, a long-sleeved shirt, and long pants to prevent accidental envenomization. During periods of local heavy infestations, children should be instructed to avoid trees, shrubs, and other vegetation commonly infested with these caterpillars. Local entomologists may be contacted to obtain information on the most effective insecticide for saddleback caterpillar control in a given area. Envenomization Reaction/Treatment. (See appendix.) BIBLIOGRAPHY General 1. Barnard, J.H. Cutaneous responses to insects. JAMA 196:3 (1966). 2. Borror, D.J., and D.M. DeLong. An introduction to the study of insects, 2d ed. New York: Holt, Rinehart and Winston, 1964. 3. Dodge, N.N. Poisonous dwellers of the desert. Popular Series No. 3, Southwestern Monuments Assoc., Box 1562, Globe, Ariz., 1955. 4. Frazier, C.A. Diagnosis and treatment of insect bites. Clin Symp 20:75-100 (1968). 5. Frazier, C.A. Insect allergy: Allergic reactions to bites of insects and other arthropods. St. Louis: Warren H. Green, Inc., 1969. 6. Frazier, C.A. Treatment guide: Common biting and stinging insects and other arthropods. West Point, Pa.: Merck Sharp & Dohme, 1972.