What's That Bug? does not endorse extermination

Subject: Black waved flannel moth
Location: Fredericksburg, Virginia
June 30, 2017 12:46 am
I’m pretty certain that these photos are of the Black Waved Flannel Moth (checking against bug guide)(and reading that you have had endless photos of them). …I got no absolute confirmation from Bugguide but there were many photos of identical moths. The information I can’t seem to find, is what relationship these moths have to the Puss Caterpillar. They seem to be separate ….there are the megalopygea opercularis and then there are the species Lagoa crispata. Both Flannel Moths? Similar looking caterpillars?.
And the Puss Caterpillar is VENOMOUS but I can’t find information on how venomous the Lagoa crispata is. Or the specific caterpillar. The internet is conflicting. Are they venomous and are they AS venomous?
Signature: Susan Warner

Black Waved Flannel Moth

Dear Susan,
All the images you provided are details.  We wish you had provided a standard dorsal view of the entire moth.  We believe your identification of the Black Waved Flannel Moth is correct, and the antennae indicate this is a male moth.  BugGuide does indicate:  “Caution, Hairs on caterpillar highly irritating, as in all of this family!”  So, the family Megalopygea includes both
Lagoa crispata and Megalopyge opercularis, but they are classified in different genera within the family.  According to an article on the Asp, Megalopyge opercularis, by David M. Eagleman on EaglemanLab:  “Envenomation from the spines of the caterpillar causes severe pain, burning, swelling, nausea, abdominal distress, and headache. … The best known venomous caterpillar in the American south- west is the puss moth caterpillar, Megalopyge opercularis, commonly called an asp, wooly asp, Italian asp, opossum bug, wooly slug, and el perrito. It is considered one of the most toxic caterpillars in North America.”  We agree with you that the two caterpillars look very similar, and it is entirely possible that some Asp postings on our site are misidentified, and are actually the caterpillars of the Black Waved Flannel Moth.  Regarding the relative venomousness of the two species, we cannot provide you with a scale or data, but we do know that irritation and reactions to stings and bites from insects vary from person to person.  Some folks are highly allergic to the sting of a Honey Bee while other folks are barely affected at all beyond the initial pain of the sting.  Some folks have tremendous reactions to the bite of a Lacewing, while others are not affected at all.  We would urge you to refrain from handling both species, though again, distinguishing between the two might be difficult.  It is also possible that the sting of the Black Waved Flannel Moth caterpillar has not been studied as extensively as has the Asp.  Of the entire Flannel Moth family Megalopygidae, the Auburn Agriculture page on Stinging Caterpillars states:  “Flannel moth caterpillars, like slug caterpillars, do not exactly fit the description of the typical lepidopterous larva. Structurally they differ in having seven pairs of prolegs rather than five (or less) pairs common to typical caterpillars. Most are clothed with fine, long, silky hairs. There are no conspicuous large, threatening, bristle-bearing “horns” to warn of danger; however, concealed within the hairy coats are venomous setae capable of producing severe reactions.”  While the Black Waved Flannel Moth is not discussed in the article, Auburn Agriculture does clearly state:  ”  Puss Caterpillar (Megalopyge opercularis) The puss caterpillar (the adult is called southern flannel moth) is our most ‘dangerous’ stinging caterpillar. Contact may produce severe reactions including: intense burning and nettling of the skin; severe pain; reddening and inflammation; development of pustules and other lesions; numbness; swelling, which may sometimes be extensive; and nausea. Pain may persist from one to twelve or more hours. In some instances, victims have required medical attention. The larva is urticating in all stages, but severity of the reaction is generally proportional to size. Also, newly molted skins retain stinging capabilities.”  There you have it.  According to Auburn Agriculture, the Asp is “our [North American] most ‘dangerous’ stinging caterpillar.”

Subject: supplement photo (dorsal)
Location: Frederericksburg
June 30, 2017 8:19 pm
I have a dorsal view of the moth…better overall….not just the detail….of the Black Waved Flannel Moth photo i sent, to help make an ABSOLUTE identification.
It seems that both the puss variety and this one are all something to avoid. I wanted to know if seeing this moth might indicate puss or super venomous caterpillars in the vicinity. A friend in the southwest once had to go to the ER after leaning on a puss caterpillar.
Subject: Black waved flannel moth
Location: Fredericksburg, Virginia
June 30, 2017 12:46 am
Signature: Susan Warner

Black Waved Flannel Moth

Dear Susan,
Thank you for sending in a supplementary dorsal view of a Black Waved Flannel Moth.

What's That Bug? does not endorse extermination

2 Responses to Black Waved Flannel Moth

  1. Susan Warner says:

    (I had to look dorsal up in the dictionary)….I have a dorsal photo….I will post it in the normal way because I’m not sure how to post it in a comment….

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