A Moth Among the Ferns

Northern Petrophora (Petrophora subaequaria)

 

I was out taking a walk Sunday afternoon and saw many different small moths flying out from hiding in the grass and blueberry bushes. Most were too small and fast to get a good look at them. The one shown above flew and ducked under some grass blades just long enough for me to get a few snapshots before it took off. Later I went out again and saw dozens of them in a forest clearing full of bracken fern. The species is Northern Petrophora (Petrophora subaequaria, Family Geometridae) and its larvae feed only on ferns with bracken fern (Pteridium aquilinum) apparently the principle host plant. Photos at Bug Guide show the larvae on fronds of Osmunda fern.

 

Some brief information on Northern Petrophora (Petrophora subaequaria)

Taxonomy
Superfamily Geometroidea (Geometrid and Swallowtail Moths)
Family Geometridae (Geometrid Moths)
Subfamily Ennominae
Tribe Lithinini
Genus/species Petrophora subaequaria

Description
Wing span to 19 mm, speckled tan forewings with yellowish veins, antemedial and postmedial lines white edged and parallel. There is a small black dot in the center of the wings.

Life cycle
As with many moths not directly injurious to crops and forestry there is little information on the life history of Northern Petrophora. With so many adult moths appearing now in my bracken field it seems that mating and egg laying occur in the spring.

Range
Northern Petrophora occurs in North America from New Brunswick to Alberta, along the Great Lakes east to New England, and then south sporadically along the Appalachians to North Carolina.

 

SOURCES

Beadle, D. and Leckie, S. (2012). Peterson Field Guide to Moths of Northeastern North America. Houghton Mifflin Harcourt Publishing Company, Boston. 640 pages.

Voss, Edward G. (1991) “Moths of the Douglas Lake Region (Emmet and Cheboygan Counties), Michigan: IV. Geometridae (Lepidoptera),” The Great Lakes Entomologist: Vol. 24 : No. 3 , Article 11. Available at: http://scholar.valpo.edu/tgle/vol24/iss3/11

Species accounts at Bug Guide, Moth Photographers Group, HOSTS,

 

 

 

A Few More Spring Flowers

 

More flowers on shrubs and trees from around here. Trees like red maple (Acer rubrum) and quaking aspen (Populus tremuloides) and shrubs such as tag alder (Alnus incana), hazel (Corylus spp.), and willow (Salix spp.) are the first flowers of spring appearing before the more familiar spring ephemeral wildflowers that grow in forests.

Soon there will be other flowers in bloom. Hepatica (Anemone americana), stalked sedge (Carex pedunculata), and wood rush (Luzula acuminata) will come into flower in the next few days. These low growing plants occupy spaces on the forest floor and today on one of my rambles I noticed that many already have unopened flower buds.

An Afternoon in the Woods

Hardwood swamp still frozen but not for long.

 

On Saturday I took a canoe trip down the little stream with the big name (West Fork of the Moose Horn River) that passes through my property to visit the western section. This area is approximately 56 acres and forested. Most of it is upland aspen and spruce forest but there is a large hardwood swamp near the southern property line.

 

Another part of the swamp (finally) thawing out. Soon this will be a flowing stream.

 

The ground was still snow covered but it was melting fast in the warm sun. I spent most of my time in a portion of a hardwood swamp looking at tree trunks for lichens and fungi. I found several lichen species previously documented from here and possibly one new species for the list. There are also a number of unknown lichen specimens to figure out.

 

 

There were two fungi that interested me. One is Phellinus igniarius, a polypore bracket fungus, that was growing on the trunk of an old quaking aspen. This fungus decays the lignin in the wood leaving behind the lighter colored cellulose and is one of the causes of white-rot in hardwood trees. The other fungus looks like P. igniarius and like it causes decay in living hardwoods. This one seems to only grow on black ash trees. It is a polypore but the pore surface looks shaggy rather than smooth. So far no luck in figuring it out.

 

 

Most of the trees in the hardwood swamp are black ash (Fraxinus nigra) with some green ash (F. pensylvanica), yellow birch (Betula allegheniensis), paper birch (B. papyrifera), American elm (Ulmus americana), quaking aspen (Populus tremuloides), and red maple (Acer rubrum). A year ago I measured the trees in the lower two-thirds of the swamp to get a population count by species and to calculate basal area. Some of the black ash trees are huge (for this part of Minnesota anyway). Of the 64 black ash measured 14 were between 28 cm and 44 cm in diameter. There were also 12 yellow birch in this size range. Black ash and yellow birch are slow growing trees even on good sites like this one so it is possible that the largest trees are at the century mark.

 

 

About a year ago

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Its hard to believe when I walk in the woods now but last year by the second week of April almost all of the snow had melted, plants were beginning to grow in sunny patches under the trees, frogs were laying eggs, and insects from bees to bugs were active. But this year everywhere I look there is deep snow and cold temperatures. In the spruce and tamarack woods there is only the occasional call of the chickadees and nuthatches. Spring flowers are a long way off.

 

Down by the stream. April 8, 2018

Are you stuck?

Laurel Sphinx Moth (Sphinx kalmiae)

 

Wandering in the woods is a favorite activity of mine and one of the ways I find new insect and other species on my land. One afternoon in mid-October while out walking along the edge of a tamarack swamp and upland deciduous-coniferous forest I saw this beautiful caterpillar with its head buried in the forest duff. Its brilliant glowing green color caught my eye immediately.  Looking more closely I saw oblique pale blue, dark blue, white, and yellow stripes on each segment. And then there was the blue horn at the tail with small black dots. Its behavior was also puzzling. Why was its head partly buried in the duff?

Caterpillars with tail horns are typically some species of the sphinx moth family (Sphingidae) although not all larvae in this family have tail horns. This made my work a bit easier than say finding some small yellow and brown striped caterpillar (a future post). The first step in finding out the species was to search for images using the phrase “green sphinx caterpillar blue stripes”. This led to an abundance of photos some of which looked like my caterpillar. One was the Tobacco Hornworm (Manduca sexta) but it lacks the yellow stripes, has blue lines in a series of dots, and the horn can be white, reddish, or yellow. A closer fit was the Wild Cherry Sphinx Moth (Sphinx drupiferarum) but it also lacks yellow stripes, has pale blue stripes, and a reddish-brown horn. As its name suggests the Wild Cherry Sphinx Moth feeds on cherry (Prunus) a few scraggly shrubs of which were in growing in the area.

None of the Sphinx Moth larva images were like this caterpillar except for the Laurel Sphinx Moth (Sphinx kalmiae).  It was off to BugGuide and the Moth Photographer’s Group where the description and photos seemed to confirm this.

Continuing my research I found another website, Sphingidae of the Americas linked from the Moth Photographers Group page on Sphinx kalmiae, that is very helpful in identifying Sphinx Moth caterpillars. Sphingidae of the Americas is dedicated to all Sphinx Moths in North, Central, and South America, and the Caribbean and includes photos of larval, pupal, and adult stages with information on distribution, flight times, and larval host plants (when known).

Description, Range, Life History of the Laurel Sphinx Moth

Principle larval host plants are in the Oleacea (Olive Family) and include species of ash (Fraxinus), fringe tree (Chionanthus virginicus), common lilac (Syringa vulgaris), and privet (Ligustrum). Laurel Sphinx Moth larva have also been reported feeding on hackberry (Celtis occidentalis, Ulmaceae), mountain laurel (Kalmia latifolia, Ericaceae), yellow bush honeysuckle (Diervilla lonicera, Caprifoliaceae), and mountain holly (Nemopanthus mucronata, Aquifoliaceae). Growing at the location where I found this caterpillar are black ash trees and yellow bush honeysuckle. There is also winterberry (Ilex verticillata) which is in the same family as mountain holly. It would be interesting to know whether the Laurel Sphinx larvae eat this also. Whether they eat mountain laurel (Kalmia latifolia) or not is questionable as the species epithet “kalmiae” is probably from the name of the 18th century naturalist Pehr Kalm and not from laurel plants (also named after him). Adult moths nectar at flowers usually at night but can be attracted to baits of fermented fruit mixed with sugar and beer.

The Laurel Sphinx Moth is a medium-sized moth with a wingspan of 7.5 to 10 cm. The forewings are yellow-brown with some fine dark brown lines along the wing veins. The reniform spot (a kidney-shaped marking found on the forewings of many moth species) is black. The underwings are also yellow-brown but with broad dark brown antemedial and postmedial bands.

Laurel Sphinx Moth occurs in the eastern half of the United States from Maine to North Carolina and west to Texas, Oklahoma, and Nebraska, and north to Newfoundland, Quebec, Ontario, Manitoba, and Saskatchewan in Canada.

Taxonomy

Class Insecta – Insects
Order Lepidoptera – (Butterflies, Skippers, and Moths)
Superfamily – Bombycoidea (Silkworm, Sphinx, and Royal Moths)
Family – Sphingidae (Sphinx Moths)
Subfamily – Sphinginae
Tribe – Sphingini
Genus and species – Sphinx kalmiae (Laurel Sphinx Moth)

So, was this caterpillar stuck in the duff or in any sort of trouble? No, as it turns out there are many moth species in Sphingidae whose larvae burrow into loose soil just before pupating which is what this one was doing. If all goes well this winter then come late May or early June an adult Laurel Sphinx Moth will emerge and begin the cycle all over again. Maybe I’ll see the adult Laurel Sphinx Moth this coming summer sipping on overripe banana mush and beer.

 

SOURCES AND MORE INFORMATION

H. M. Bower (1961). Food Plants of Sphingidae in Wisconsin. Journal of the Lepidopterists’ Society. Vol.15 , No. 1:64.

H. M. Bower (1963). Additional Note on Food Plant of Sphinx kalmiae. Journal of the Lepidopterists’ Society. Vol. 1, No. 17:36.

R. W Hodges (1971). The Moths of America North of Mexico. Fasicle 21. Sphingoidae. Hawkmoths. London, E. W. Classey: 158 pages.

C. Messenger (1997). The Sphinx Moths (Lepidoptera: Sphingidae) of Nebraska. Transactions of the Nebraska Academy of Sciences, 24: 89-141.

A. P. Platt (1969). A light weight collapsible bait trap for Lepidoptera. Vol. 23, No. :97-101.

Bug Guide website

Moth Photographers Group website

Butterflies and Moths of North America website

Sphingidae of the Americas website