Bug o’the Week – Anglewings

Howdy, BugFans,


The BugLady was chasing a very jumpy Eastern Comma butterfly around her driveway (with a camera) the other day.  Commas are in the Brushfoot family, Nymphalidae, in the genus Polygonia (Greek for “many angles” – remember high school geometry?), a group that’s called, for obvious reasons, “anglewings.”  She found an article that dubs them “Butterflies That Punctuate,” because of the distinct, white/silver mark on the underside of the hind wing.  Anglewings are among the last butterflies abroad in fall and the first in spring (and sometimes in-between).  What follows is a major overhaul of a BOTW from 2009.


In general, insects spend just a few months (or less) in their adult skins, and most adult insects die with the first frosts, leaving the next generation behind in the form of eggs or pupae (or, less commonly, as nymphs or larvae).  Wisconsin’s anglewings overwinter as adults (as do members of the genus Nymphalis, which includes the Mourning Cloak).

Adults spend the winter tucked into spaces called hibernacula (singular – hibernaculum) – cracks and crevices in rock piles and tree bark or under eaves.  They may emerge on an especially warm winter day and then shelter again.  Because their blood contains glycerol – antifreeze – their tissues avoid cell damage while withstanding the winter’s cycles of freezing and thawing.


Some species of anglewings produce two generations a year in Wisconsin and others have a single brood.  Second-brood anglewings that emerge in late summer to fly in fall are seven or eight months old by the time they breed during the following spring – supercentenarians by butterfly standards.  Summer and winter adults have somewhat different coloration; the top surface of the hind wing is more uniformly dark in the summer butterflies, the “umbrosia” form.  Just as their winter counterparts doze through the cold weather, the summer forms may become dormant in response to the heat.


The lack of flowers at the start and end of their flight period bothers these butterflies not at all; they have alternate menu options.

Two common anglewings in Southeastern Wisconsin are the Eastern Comma and the Question Mark; (check out Mike Reese’s Wisconsin Butterflies website for information about the state’s commas: https://wisconsinbutterflies.org/butterfly/subfamily/17-true-brushfoots.

Birders who are diving into Gull identification are advised to study the Herring Gull in all of its ages/stages/plumages in order to compare them to other gulls (FYI, there are many different kinds of gulls, but there is no species called a Sea Gull.  If you’re not sure what kind it is or are referring to them collectively, just saying “gull(s)” will do.  Different pulpit).  Anyway, in taking on the anglewings, learning the Eastern Comma seems like a good place to start (the BugLady has no doubt that she has some mislabeled comma pictures in her files).


The EASTERN COMMA (Polygonia comma) is also called the Hop Merchant.  Hops are one of its larval food plants, and hop growers historically considered the metallic flecks on the chrysalis http://bugguide.net/node/view/924296/bgimage to be a portent of what their crops might bring at the market.  Silver markings meant low prices; gold meant high.

It’s a wary butterfly, one that flies swiftly and erratically, and when it ducks into the vegetation and perches (often head-down on a tree trunk), its dead-leaf/wood-grained underwings make it tough to see.  Eastern Commas will sit on people, crawling around until they find the right exposure and then basking.  Douglas and Douglas, in Butterflies of the Great Lakes Region, report that Eastern Commas will seek sweat on people’s skin, often searching disconcertingly close to the eyes of their human perches.  Males defend their “pied a terre” aggressively.

Eggs are laid, sometimes in stacks, on the underside of host plant leaves.  Eastern Comma caterpillars feed at night, on nettles, elm and hops.  It’s one of the species that seems to have broadened its palette as European settlers brought hops and non-native nettles (an important fiber plant) to the Northeast.  The caterpillars, according to David L. Wagner in the awesome Caterpillars of Eastern North America, will select a leaf and fold the edges under with silk to make a daytime shelter.

Adults sometimes visit flowers, but they generally sip from sap drips on tree trunks, imbibe the juices exuded by rotting fruits and berries, and absorb salts and minerals from animal droppings and from the ground (each time it landed, her driveway comma extended its proboscis and probed the gravel for minerals).

The Eastern Comma is sometimes described as an inconspicuous butterfly, but the BugLady humbly disagrees.  While it can be extraordinarily well-camouflaged, an individual sunning itself on the dead leaves of the forest floor glows like a small flame.

QUESTION MARKS (Polygonia interrogationis) are handsome, medium-to-large sized (wingspread about 2 ½”) anglewings that have a white/silver question mark on the underwing – though Samuel Scudder preferred the name “Violet-tip” (because of the edges of the winter form’s hind wings) and nineteenth century American entomologist Thaddeus Harris called them the “Semicolon butterfly” (it’s all about perspective).  Their underwings may be leafy-looking or be a fairly uniform in color.


Male Question Marks are described as “pugnacious,” flying out from sunny perches to greet visiting females and to deter rival males (and sometimes other intruding insects and even birds).  Like other anglewings, they will land on people who are standing really still (especially in the sunlight) and probe for sweat.

They feed on tree sap, rotting fruit, and nutrients in soil, carrion and dung; females are more likely to nectar from flowers than males are.  According to Robert Michael Pyle in The Audubon Society Field Guide to North American Butterflies, anglewings are prone to intoxication if the fruit they sip from has been fermenting in the sun too long.  They are “quiet drunks” – an inebriated Question Mark may pose for pictures and finally tuck in its legs and play dead.


Question Marks have two broods each year in our neck of the woods.  Females lay their eggs in stacks under the leaves of hackberry, hops, nettle and elm, and while they’re not super-gregarious, the resulting caterpillars may tolerate nearby siblings.  They don’t make leaf nests.  Like other anglewing caterpillars, Question Mark larvae are decorated with non-toxic, branched spines called scoli (singular – scolus), including a pair of spines on their head http://bugguide.net/node/view/1129753/bgimage.

Along the Atlantic coast, Question Marks are both residents and migrants, so early spring sightings could either be recently-awakened or recently-arrived.  Their migratory status in Wisconsin is unknown, but migration is a handy arrow to have in your quiver where the winters get a little brisk.

The BugLady’s searches took her, once again, to the Butterflies of Massachusetts website, where nearly two centuries of data are thoughtfully analyzed and where changes in butterfly populations with shifting land use patterns/habitat changes are documented.  For lots of information, see http://www.butterfliesofmassachusetts.net/eastern-comma.htm and http://www.butterfliesofmassachusetts.net/question-mark.htm.

View the Eastern Comma and the Question Mark side-by-side at http://trekohio.com/2013/04/24/butterflies-that-punctuate-the-eastern-comma-and-the-question-mark/ and


In the “Wow – Who Knew??” category see https://en.wikipedia.org/wiki/Glossary_of_entomology_terms

And here’s a jumping spider follow-up: http://www.npr.org/sections/thetwo-way/2016/10/14/497931790/a-spider-across-the-room-can-hear-you-study-finds.  Thanks, BugFan Laurel.  “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ (I found it) but ‘That’s funny…‘”–Isaac Asimov

Kate Redmond, The BugLady

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