Bug o’the Week – Small Magpie Moth Mystery

Greetings, BugFans,

A few days ago, the BugLady was mulling over which insect she was going to feature in the next BOTW.  She headed out the door to hike to the mailbox, and there, on the inside of the storm door, trapped between it and the back door, sat this beautiful Small magpie moth.  The BugLady managed a few mediocre shots (on a west-facing glass door at twilight), but happily, other people have done better: https://bugguide.net/node/view/105683 (some have a broader band on the edge of the wing https://bugguide.net/node/view/1187270/bgimage),  https://bugguide.net/node/view/527448https://bugguide.net/node/view/1475330/bgimage,

https://bugguide.net/node/view/20549/bgimage, and https://bugguide.net/node/view/141026/bgimage.

Small magpie moths (Anania hortulata) are in the Crambid snout moth family Crambidae. Overall, it’s a pretty drab group of moths, with some delightful exceptions like these, of previous BOTW fame: Bi-colored pyrausta https://bugguide.net/node/view/851405/bgpage, Orange mint moth https://bugguide.net/node/view/1119674/bgimage, Raspberry pyrausta https://bugguide.net/node/view/1382922/bgimage and the White-spotted sable https://bugguide.net/node/view/37715/bgimage.  Crambidae is a small family of 157 mostly-tropical species; their larvae conceal themselves in fruits, stems, or rolled/webbed-together leaves while eating.

They’re in the subfamily Pyraustinae, and according to bugguide.net, Pliny the Elder said that Pyrausta was, “a winged insect that was supposed to live in fire.”  “Magpie” apparently refers to the moth’s flashy black and white scales (there’s a Clouded magpie and a regular magpie moth, too: http://www.wildlifeinsight.com/british-moths/magpie-moth-caterpillar-abraxas-grossulariata/, but not here).

Small magpie moths, it turns out, are not native to North America – they are at home across Eurasia – so the majority of the biographical information the BugLady found was on English nature websites (but, FYI, their Norwegian name is Nesleengmott).  They probably arrived on this continent (at Nova Scotia) in the late 1800’s, and their checkerboard range now includes the Canadian Maritimes and New England states, Quebec, Ontario, Michigan and Wisconsin (with a southern outlier specimen from Maryland), and the Pacific Northwest, to which, according to one source, they were introduced.

When they’re not sitting on storm doors (and it’s not winter), Small magpie moths are found in gardens, edges, hedgerows, and weedy waste spaces.  The BugLady could find no mention of the adults feeding, but the caterpillar https://bugguide.net/node/view/43983/bgimage eats the leaves of nettles (mostly), plus various mints, and bindweed.

There’s only one generation a year – caterpillars make a cocoon in a concealed spot in fall and spend the winter in it, pupating in spring without leaving the cocoon.  They emerge as adults not long after, with a May-to-September flight period.

But here’s the deal.  There’s no way this adult moth should have been on the landscape this week.  Yes, it’s been a mostly-mild winter here (once we got through November), and yes, the UK Butterfly Conservation site says that they “can be recorded as early as February and sometimes as late as November,” but it’s warmer overall in England, with the Gulf Stream, and all.  And one source says that larvae sometimes overwinter in attics (which the BugLady doesn’t have).  So where did this moth come from?  (And where did it go?  The BugLady looked down to fiddle with her camera and when she looked up again, the moth was gone – presumably into the house – no sightings yet.)

Rabbit hole alert:

For those who want to pursue the Pliny translation further, bugguide.net offers this link to the Tufts University Perseus Digital Library and Pliny’s writings about “An Animal Found in Fire” http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.02.0137%3Abook%3D11%3Achapter%3D42.  “That element, also, which is so destructive to matter, produces certain animals; for in the copper-smelting furnaces of Cyprus, in the very midst of the fire, there is to be seen flying about a four-footed animal with wings, the size of a large fly: this creature is called the ” pyrallis,” and by some the ” pyrausta.” So long as it remains in the fire it will live, but if it comes out and flies a little distance from it, it will instantly die.”  (Nota bene – there are little blue “forward” and “back” arrows if you can’t get enough Pliny).

Kate Redmond, The BugLady

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