Megalopyge opercularis

{{multiple image | direction = vertical | width = 250 | image1 = Furry Puss Caterpillar 2014.JPG | caption1 = M. opercularis caterpillar on Kent Island, Maryland | image2 = Megalopyge opercularis coccoon.jpg | caption2 = Cocoon}}

The inch-long larva is generously coated in long, luxuriant hair-like setae, making it resemble a tiny Persian cat, the characteristic that presumably gave it the name "puss." It is variable in color, from downy, grayish white to golden brown to dark, charcoal gray. It often has a streak of bright orange running longitudinally. The "fur" on early-stage larvae is sometimes extremely curly, giving them a cottony, puffed-up look. The body tapers to a tail that extends well beyond the body, unlike its relative M. crispata. The middle instar has a more disheveled, "bad-hair-day" appearance, without a distinctive tail. The "fur" of the larva contains venomous spines that cause extremely painful reactions in human skin upon contact. The adult moth is covered in long fur in colors ranging from dull orange to lemon yellow, with hairy legs and fuzzy black feet.{{citation needed|date=August 2024}} The cocoons that these caterpillars emerge from vary in size from 1.3 to 2.0 centimeters and contain small hair pockets on the back and flattened front end, the latter covering the operculum at least until it is completely formed.{{cite journal|title=Puss Caterpillar (Larva), Southern Flannel Moth (Adult), Megalopyge opercularis (J. E. Smith 1797) (Insecta: Lepidoptera: Zygaenoidea: Megalopygidae)|url=https://edis.ifas.ufl.edu/publication/IN976|last=Hall|first=Donald W.|date=25 April 2022|journal=Edis|volume=2013 |publisher=University of Florida Institute for Food and Agricultural Sciences Extension|access-date=1 August 2024|doi=10.32473/edis-in976-2013|id=Pub. No. EENY-545|orig-date=Originally published January 2013}}

M. opercularis can be found on oak, elm, and wild plum, among others, as well as many garden plants such as roses and ivy. It is distributed throughout the Eastern United States between extreme southeastern Virginia and Florida, the Southern United States, Mexico, and parts of Central America and South America. The caterpillar has two broods, one in the summer and the other in the fall. Late larvae may stay in their cocoon all winter, and emerge in late spring as an adult.

The caterpillar is regarded as a dangerous insect because of its venomous spines. Exposure to the caterpillar's fur-like spines leads to an immediate skin irritation characterized by a "grid-like hemorrhagic papular eruption with severe radiating pain." Victims describe the pain as similar to a broken bone or blunt-force trauma, or even white hot.{{Cite web|url=https://www.nbc12.com/2020/09/11/venomous-caterpillar-no-one-has-heard-sends-new-kent-woman-er/|title = Venomous caterpillar 'no one has heard of' sends New Kent woman to ER| date=11 September 2020 }} The reactions are sometimes localized to the affected area, but are often very severe, radiating up a limb and causing burning, swelling, nausea, headache, abdominal distress, rashes, blisters, and sometimes chest pain, numbness, or difficulty breathing.{{cite news|last= Demkovich|first=Laurel|title='BE AWARE': Pasco mom posts to Facebook after son's caterpillar sting leads to ER trip|work=Tampa Bay Times|date=June 20, 2018|url=https://www.tampabay.com/news/health/-BE-AWARE-Pasco-mom-posts-to-Facebook-after-son-s-caterpillar-sting-leads-to-ER-trip_169327170/

|access-date=2018-06-21}}

Sweating from the welts or hives at the site of the sting is not unusual.{{Cite journal|last=Eagleman|first=David M.|date=January 2008|title=Envenomation by the asp caterpillar ( Megalopyge opercularis )|url=http://www.tandfonline.com/doi/full/10.1080/15563650701227729|journal=Clinical Toxicology|language=en|volume=46|issue=3|pages=201–205|doi=10.1080/15563650701227729|pmid=18344102|s2cid=15696836|issn=1556-3650|url-access=subscription}}

The venom from the spines is best treated within hours of first contact. For first aid, the spines (if present) should be removed by using cellophane tape. Some remedies, which are reported to have varying degrees of success, include ice packs, oral antihistamine, baking soda, hydrocortisone cream, juice from the stems of comfrey plants, and calamine lotion. The caterpillar sting causes a condition called urticarial dermatitis or erucism, with M. opercularis contact being the most commonly reported source in the United States.{{cite journal|last1=Michienzi|first1=Avery E.|last2=Holstege|first2=Erik P.|last3=Cole|first3=Ryan J.|last4=Charlton|first4=Nathan P.|title=The Sting of a White Flannel Moth Caterpillar (Norape ovina)|journal=Wilderness & Environmental Medicine|doi=10.1016/j.wem.2022.03.011|volume=33|issue=3|year=2022|doi-access=free|pages=329–331|pmid=35577658 }}

{{Reflist|refs=

{{ cite journal | last = Eagleman | first = David M. | title = Envenomation by the asp caterpillar (Megalopyge opercularis) | journal = Clinical Toxicology | year = 2007 | volume = 46 | issue = 3 | pages = 201–205 | doi = 10.1080/15563650701227729 | pmid=18344102| s2cid = 15696836 }}

{{Cite journal |title=Caterpillars and moths | first=Eric W. |last=Hossler | journal=Dermatologic Therapy | year=2009 | volume=22 | issue=4 | pages=353–366 | doi=10.1111/j.1529-8019.2009.01247.x | pmid=19580579| s2cid=31799282 | doi-access=free }}

{{cite journal|last1=McGovern|first1=John P.|last2=Barkin|first2=Gilbert D.|last3=McElhenney|first3=Thomas R.|last4=Wende|first4=Reubin|title=Megalopyge opercularis: Observations of Its Life History, Natural History of Its Sting in Man, and Report of an Epidemic|journal=JAMA|date=1961|volume=175|issue=13|pages=1155–1158|doi=10.1001/jama.1961.03040130039009}}

{{cite book | last=Wagner | first=David L. | year=2005 | title=Caterpillars of Eastern North America | publisher=Princeton Univ. Press|chapter=Flannel Moths – Megalopygidae|chapter-url=https://muse.jhu.edu/chapter/1263599|page=55| isbn=1400834147 |chapter-url-access=subscription|url=https://books.google.com/books?id=F8Ur63KP538C&pg=PA55}}

{{cite journal|last1=Simmons|first1=Alvin M.|last2=Wiseman|first2=B. R.|title=James Edward Smith - Taxonomic Author of the Fall Armyworm|journal=The Florida Entomologist|date=1993|volume=76|issue=2|page=275|doi=10.2307/3495726|jstor=3495726|url=http://journals.fcla.edu/flaent/article/view/58943|url-access=subscription}}

{{cite book|last1=Smith|first1=James Edward|title=The Natural History of the Rarer Lepidopterous Insects of Georgia. Including their systematic characters, the particulars of their several metamorphoses, and the plants on which they feed. Collected from the observation of Mr. John Abbot, many years resident in that country|date=1797|publisher=T. Bensley|location=London|pages=105–106|chapter-url=https://biodiversitylibrary.org/page/269163|chapter=Tab. LIII. Phalæna opercularis|volume=2}}

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• {{wikispecies-inline|Megalopyge opercularis|Megalopyge opercularis}}
• {{Commons category-inline|Megalopyge opercularis|Megalopyge opercularis}}
• [https://archive.today/20121212010357/http://neuro.bcm.edu/eagleman/asp Research on the Asp Caterpillar at Baylor College of Medicine]
• [http://entnemdept.ufl.edu/Creatures/MISC/MOTHS/puss.htm Megalopyge opercularis] on the UF / IFAS Featured Creatures website.

{{Taxonbar|from=Q4043912}}

Category:Moths described in 1797

Category:Megalopygidae