Unknown Canadian Moth is Four Spotted Ghost Moth

July 16, 2010
Fort Saskatchewan, Alberta, Canada
I saw this moth on my deck today and am very curious what it is. I am located in Alberta Canada and have never seen one of these before.

Four Spotted Ghost Moth

Dear Brent,
Alas, we do not recognize your moth.  We discovered a Moths of Canada Website, but we did not have any luck with a proper identification.  We will post your letter and hope one of our readers can assist with this identification.

Four Spotted Ghost Moth

I was on that site too and couldnt find anything, thanks a lot for your help!!! I’ll check your site from time to time and to see if someone knows…thanks again!!!

Thanks so much to Markidavana who provided a comment identifying this Four Spotted Ghost Moth, Sthenopis purpurascens.  Interestingly, when we went to BugGuide to create a link, we found Brent’s photos already posted and identified.  There was not much information on this species on BugGuide, but we did learn that this moth is in a family, Hepialidae,  that has not been represented previously on What’s That Bug? so we created a new category for it.  BugGuide does provide family information, including:  “””to attract females, the male hovers over open ground, sometimes slowly rising and falling [like a ghost]” which is credited to Wikipedia.  BugGuide also indicates:  “Early instar larvae feed on plant detritus, decaying wood, or fungi; later instars bore into roots or stems of woody plants, or feed on moss, and the leaves of grasses and other herbaceous plants.  Some adults cannot feed because they lack mouthparts” and “Considered a ‘primitive’ moth because of a combination of adult and larval characters. Adult moths lack a strong wing coupling mechanism and instead use a ‘jugum’, which is a thumb like projection between fore- and hindwings. Wings do not remain coupled while in flight. While present in other primitive lepidoptera, the exact function remains speculative. This feature is often strongly, and best, developed in the Hepialidae. Adults also have reduced or sometimes absent mouthparts.”  The Entomology Collection of the University of Alberta website also has some interesting information, including:  “habitat Mature mixedwood and poplar forest, in particular near wetlands.  seasonality Adults fly in Alberta from early July through mid-August, peaking the last half of July. identification Adults are large (6.6-10.0 cm wingspan) long-winged moths that occur in two color forms, purple-grey and yellow-brown. Until recently the yellow-brown form was thought to be a separate species, S. quadriguttatus. The forewings have a darker oblique median band, a darker terminal area and darker spots along the costa. There are two small, silver spots near the wing base. Hindwings are even purple brown or salmon pink, unmarked except for one or two small spots on the outer part of the leading edge. The antennae in both sexes are greatly reduced and hair-like, and separate them from all other large Alberta moths. The similar S. argenteomaculatus (Harris) does not occur in Alberta, and the literature reports for argentomaculatus are errors (Schmidt and Lawrie, 1999). life history Females deposit eggs in the vicinity of the host while in flight. The larvae bore into the roots of poplars, willows or alder where they complete the life cycle. The larvae apparently take two years to complete the lifecycle, and adults in Alberta are more common in odd-numbered years. Mature larvae are about 50-60 cm long, with cream-white bodies, brown heads and brown bases of the setae. The adults are crepuscular and are poorly attracted to light. conservation A fairly common, widespread insect; no concerns. diet info Larvae bore into the roots of poplars (Populus sp.), and to a lesser extent willow (Salix) and alder (Alnus). range Labrador and New York north and west to British Columbia and the Northwest Territories, south in the mountains to Arizona. In Alberta, it is most common throughout the Boreal forest and Aspen Parkland regions, less common in the Foothills and Mountains, and along wooded parts of the valleys in the Grasslands region.”   While writing our book, we did learn this information on a moth in the same family, the Australian Ghost Moth on the University of Florida Book of Insect Records :  “The highest lifetime fecundity among non-social insects appears to be a lepidopteran. An Australian ghost moth female, Trictena atripalpis (Hepialidae), captured at Adelaide, laid 29,100 eggs (Tindale 1932), and when it was dissected 15,000 eggs were found in the ovaries. These moths oviposit while in flight and tend to lay their eggs in the vicinity of the red gumtree (Eucalyptus rostrata), on the roots of which their larvae feed. There are other ghost moths that are larger, which may have an even higher fecundity, but I’ve found no literature on egg number in these species.

Thanks so much for all your help! I couldn’t believe how fast I got an answer about that moth!!! I’ll be sure you use this site again next time I have a question. Thanks!!

3 thoughts on “Unknown Canadian Moth is Four Spotted Ghost Moth”

    • Thanks so much Mardikavana. Your identification allowed us to do considerably more research on this fascinating Four Spotted Ghost Moth.

  1. This moth is also in humboldt Saskatchewan , and seemed to have disappeared considerably , when the fire was thick by p.a these moths showed up basically covering walls completely , over the next three or four days they coated (the stems of tall grass and even electrical cords outlets and basically anything really ) in a thick black tar like substance , if you squish one they have black inside them also but attached are white blobls , looks like eggs honesty so it’s obviously it’s hatching process, what I’m curios to know is how in hello half acre is a guy supposed to get it off ? I work at an industrial wash bay , our water is 140 degrees celcius all day , doesn’t touch the tar , I have tried multiple cleaners , spray nine, citrus solve, pansolve ( can take practically anything off , tar from roadways comes off with pan solve but no not this moth tar ? It be cool to know what the heck it is , or made up of ? Is it harmful ?


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