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Southern Flannel Moth (Megalopyge opercularis)

Detailing the physical features, habits, territorial reach and other identifying qualities of the Southern Flannel Moth.

 Updated: 8/23/2019; Authored By Staff Writer; Content ¬©

Where there are fluffy Southern Flannel Moth adults, there will be their harmful, stinging, furry caterpillars.

While adult Southern Flannel Moths are striking to behold, the larvae of this species is capable of delivering a sting so painful, some liken the sensation to a sudden amputation. The caterpillars are sometimes called Asp Caterpillars because contact with one feels like a snake bite. Extreme caution must be practiced in areas where these caterpillars may roam. Long, yellow hairs cover the entire body, giving it a soft, pet-able appearance. The resemblance to cat fur donned them the moniker 'Puss Caterpillar'. These stinging hairs have a toxic venom inside them. The older the caterpillar, the more potent the chemical defense. Merely brushing past the hairs can cause them to break off and inject this venom. The hairs may even embed themselves in skin and need to be removed (using tape or tweezers, not fingers). Pain begins within minutes and increases exponentially, possibly spreading throughout the whole limb or affected area. Typically, redness and swelling develop at the wound. The sting is not lethal, but it causes extreme discomfort. Removing hairs, applying a cold compress, and taking pain medication as well as allergy medication are common courses of treatment. Medical attention can help quickly relieve pain in children, who are especially sensitive and most likely to have contact.

Caterpillars feed on the foliage of a variety of plants, including oak and elm trees. These trees are common in playgrounds, backyards, and parks. Children are at high risk of contact, so teaching them to identify and avoid this caterpillar is highly suggested. (Out of an abundance of caution, adults and children alike should not touch hairy caterpillars unless they know them to be safe to handle.) Two broods are produced each year. In the Deep South, Texas, and Mexico, three broods are produced. If adult moths are seen in an areas, it should serve as an early warning to be on the lookout for the near arrival of stinging larvae.

Adult moths, however, do not sting. They are covered in thick hairs, almost like fur, or soft flannel. The yellow moth has large swaths of brown color on each forewing with white hairs covering them. Dark spots are scattered inside the brown areas. The bottoms of the forewings are pale. The thorax is inundated with orange hair. Legs are covered in yellow hairs as well and its feet are black. White antennae have black tips and are comb-like.

Natural parasites of the caterpillar include Tachinid Flies and some species of wasp. Once the caterpillar forms its cocoon, female wasps injects their own eggs inside it and the intruding larvae eat the caterpillar after hatching. Old cocoons are repurposed by spiders and other insects as shelters.
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Taxonomic Hierarchy
Kingdom: Animalia
  Phylum: Arthropoda
    Class: Insecta
      Order: Lepidoptera
        Family: Megalopygidae
          Genus: Megalopyge
            Species: opercularis
Identifying Information
Scientific Name: Megalopyge opercularis
Other Name(s): Puss Caterpillar, Asp Caterpillar
Category: Butterfly or Moth
Size (Adult; Length): 24mm to 36mm (0.94in to 1.40in)
Colorwheel Graphic Colors: yellow, orange, brown, white, black
Descriptors: furry, fluffy, fuzzy, hairy, painful, stinging, wave, flying
Territorial Map
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Territorial Reach (A-to-Z)
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Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.

Butterfly and Moth Anatomy
Graphic showing basic anatomy of a common North American butterfly and moth insect
Antennae: Butterflies and Moths have a pair of antennae on the head used as sensors.
Head: The head is home to the insect's eyes, antennae, and proboscis.
Thorax: Home to the three pairs of legs as well as vital internal organs.
Abdomen: Contains vital internal organs such as the heart(s) and reproduction facilities.
Forewing: The upper, forward wing pair used for flying.
Hindwing: The lower, rearward wing pair used for flying.
NOTE: Butterflies and Moths are part of the Lepidopteran order as they share many similarities.