Problems with Photographic Identification of Moths

The purpose of this page, and the series of pages that will be developed in this section, is to introduce the non-technical reader to some of the problems of moth identification. Many persons who avidly seek to photograph moths and other natural history subjects have had little exposure to the entomological literature and may have few popular works dealing with moths.

To aid thinking about the problem it might be helpful to consider the differences in North America where one may find on the order of 11,000 species of moths, 700 butterflies or birds, and perhaps 600 odenates (dragonflies and damselflies). The study of birds and butterflies has been more intense, and over many more years, both among professional biologists and amateur hobbyists than has been the case for moths or odenates. There are many popular field guides for birds and butterflies which cover all of the described species north of Mexico (excepting recently discovered forms, invasive species and perhaps rare migrants). For birds and butterflies, species recognition is not a particularly acute problem. Bird song helps to distinguish species that may be difficult to separate visually. Many amateur birders are able to identify all the species found in their locality or region, especially after a few years of field experience.

Dragonflies and damselflies have not had much popular following until recent years, hence there have been fewer field guides produced for them. There is as yet no complete popular guide covering all the species north of Mexico although a Stokes guide covers the most common species and there are a number of good state or regional works. Photos of most of the species can be found on the Internet with a bit of effort.

One of the problems with moths is the sheer number of species (too many to picture and describe in any field guide covering North America). Beyond that, however, is that unlike birds, butterflies and odenates, there is a much larger percentage of moths that simply cannot be absolutely distinguished at the species level by easy visual cues. Eyeballing a moth on a wall or taking its photograph may simply not give you the information necessary to identify the species. It might require examination of body parts (antennae, scales, internal genitalia) under high magnification to know absolutely to what species a specimen belongs.

In some cases word descriptions in the form of keys to classification can help with identification IF the specimen or photograph is in good condition. Typically, we encounter moths showing at least some degree of wear -- scales are rubbed off, obliterating critical markings. While it might be possible to "key out" fresh specimens of a species, it may be impossible to do if the specimen is worn (or if the photograph fails to capture or distorts key features).

Because of such problems we must be prepared to accept the fact that not all specimens or photographs of moths can be identified down to the level of species. Sometimes we have to be satisfied if we can discern the species group, genus or family.

The genus Eupsilia, which includes some of the moths known as Sallows, is one of the problematic groups. There are nine or ten species in North America, with perhaps more to be eventually described. A few are western species, but there are at least seven species in the east, including one or two in the process of being validated and described. All of the eastern forms are shown on this page, along with a dichotomous key to aid in the identification of six of them (known at the time the key was written 50 years ago). A few of the species key out easily, especially if the specimen is not worn. Adults encountered in mid to late winter will be worn to some degree. But three species can be separated only by examining wing scales (1) or by expert genitalic examination (2). The Forbes' Key presented below describes these features.

You will notice that the text of the key often refers to features that are variable, complicating somewhat the process of being lead to one and only one conclusion. The top portion of the key, which consists of dichotomous pairs of observable features, will lead the read to descriptive text in the bottom portion of the key. There you will also find one or more photographs for each species, as well as some photos of species belonging to this group but have not yet been officially described.

The Eupsilia Species Group -- 9933-9939
Photographs are the copyrighted property of each photographer listed. Contact individual photographers for permission to use for any purpose.

Covell Field Guide p.114; Pl. 24(12): Straight-toothed Sallow, Eupsilia vinulenta. The text states: Reniform spot white or orange, with dots above or below larger middle spot. Scales on FW end in 4 straight teeth. Under "similar species" we find: The following Eupsilia species (not shown) are almost identical in color and pattern but have curled teeth on FW scales (visible under microscope); (1) Sidus Sallow, E. sidus, and (2) Franclemont's Sallow, E. cirripalea, can be distinguished only by genitalic features. (3) Three-spotted Sallow, E. tristigmata, has FW mottled with purple, and dark spot below orange patch in reniform spot. In The Owlet Moths of Ohio the use of a 10x-20x magnifier is advised. The wing of E. vinulenta will appear to be smooth. The wings of E. sidus and E. cirripalea will have the appearance of steel wool. Readers may find useful the dichotomous key reproduced below.

Forbes' Dichotomous Key for Six Eupsilia Species
[ 1 ] - 9935 - E. tristigmata
Three-spotted Sallow Moth
Robert Patterson

[ 2 ] - 9933.1 - E. sidus
Sidus Sallow Moth
Hugh McGuinness

[ 3 ] - 9934 - E. cirripalea
Franclemont's Sallow Moth
James Adams

Juxta - Eupsilia vinulenta
Anthony W. Thomas

Key to Eupsilia Species
pp.149-151 in: Forbes, W.T.M. 1954.

Lepidoptera of New York and Neighboring States

Noctuidae Part III

Cornell University Agricultural Experiment Station. Memoir 329. 433 p.


Postmedial line pale and even, nearly straight....................................................2


Postmedial line more sinuous, definitely dentate on M1, M2-Cu2..........................3


A strong straight white stripe in subterminal area, besides the normal but often weaker postmedial and subterminal lines.................................................6. devia


No extra line in subterminal area ......................................................5. morrisoni


Reniform large, kidney shaped and orange, with a black shade in the base; the orbicular distinct, claviform usually distinct.......................................1. tristigmata


Reniform is a small spot, orange, yellow or white, usually flanked by two white points; orbicular almost always absent, but sometimes faintly discernible; claviform is obsolete......................................................................................................4


Scales of fore wing with the outer angles drawn out into long divergent spines, much longer than width of scales......................................................................5


Scales with the outer angles only moderately produced, juxta of male with no central projection, the upper part somewhat produced and rather narrow; the ductus bursae of female with heavy areas of chitinization, bursa with four signa...............................................................................................4. vinulenta


Outer margin of forewing strongly crenulate, color rather leather brown in perfect specimens; juxta of male with large central conical projection; ductus bursae of female without chitinizations, bursa with two signa..............................3. cirripalea


Outer margin almost even,  crenulations hardly noticeable,  well rounded over, color more reddish than brown; juxta of male without a central projection, the upper part wide, narrowing rather gradually; ductus bursae of female with chitinization at entrance into bursa, bursa with four signa................................................2. sidus

Genitalic Slide of E. vinulenta
Anthony W. Thomas
Line drawings at left are from Forbes' 1954 publication.

[ 4 ] - 9933 - E. vinulenta
Straight-toothed Sallow Moth
Anthony W. Thomas

[ 4 ] - 9933 - E. vinulenta
Straight-toothed Sallow Moth
Robert Patterson

[ 5 ] - 9936 - E. morrisoni
Morrison's Sallow Moth
Hugh McGuinness

[ 6 ] - 9939 - E. devia
Lost Sallow Moth
Robert Patterson

Tony Thomas has provided us with excellent examples from microscopic slides of the genitalia of Eupsilia vinulenta. While it may take training to recognize and understand genitalic differences between species, these slides and Forbes' line drawing provide a good introduction to the subject. The slide of the full genitalic preparation includes valve and juxta which are here also shown separately. The valve and juxta are easily compared with Forbes' c21. Thus, it appears that in Forbes' publication the drawings of E.sidus and E. vinulenta have been transposed.

Valve of E. vinulenta -- Anthony W. Thomas

[ 1 ] -- Eupsilia tristigmata -- 9935 -- Three-spotted Sallow Moth -- [ Text from Forbes 1954 ]

Ground variable from dull orange marked with dull indian red to dull ochre, marked with fuscous; more mottled than the other species; antemedial and postmedial lines similar, double, the line facing the median area continuous, the other weaker and often punctiform in the postmedial; antemedial nearly straight and erect; postmedial irregular, the inner line showing teeth on M1 and M2 and below, but concave across M2 and more strongly across fold; orbicular normally a paler filled ring; reniform when fully developed broad-reniform, with an orange inner lunule followed by a small but thick rounded spot, flanked above and below by light points, the lower one preceded by a blackish spot, often with the central outer spot pale or even white, the points at upper and lower ends either white or obscure, or the lower one white; claviform and narrow oblong, sometimes absent; subterminal line pale, irregular, preceded by a series of patches of the darker reddish or fuscous, and followed by a more continuous shade. Hind wing light fuscous with pale fringe and costal area. 30-35 mm.

October to April. Larva (Dyar) warm deep brown, with dorsal and subdorsal lines weak, and a broad stigmatal line tinted with orange yellow.

Nova Scotia to British Columbia and Washington, south to the vicinity of Washington, D.C. and Colorado.

Robert Patterson Robert Patterson Anthony W. Thomas

The two photos, above at left, are of the same moth, the leftmost one taken indoors under artificial light with the moth holding its wings slightly above the normal horizontal position at rest. The photo with black background was taken at night, using the camera flash, with the wings at normal rest position, almost parallel with the resting surface.. Close comparison of the two photos do not reveal equally the same diagnostic features pointed out in Tony Thomas' graphic. The nighttime photo keys out easily. The daytime photo does not do so quite as well.

[ 2 ] -- Eupsilia sidus -- 9933.1 -- Sidus Sallow Moth -- [ Text from Forbes 1954 ]

This, the preceding and following species are distinguished from all other Noctuidae discussed here by the wing scales, which are narrow, somewhat curled, with the two outermost teeth drawn out into long divergent curving spines, which interlock and give the wings a sort of shredded wheat effect. The wings are somewhat broader than in vinulenta, with a duller look and a rather brick red color; the antemedial line usually shows some waviness; the lines are rather narrow and often quite inconspicuous; the reniform spot is yellow (typical), white or pale orange, and with a tendency to be rounder than in vinulenta. The outer margin of the fore wing is almost straight but shows in absolutely fresh specimens the typical toothed margin, but much rounded over. Some specimens show a vague hint of the orbicular. The male genitalia are distinguished from vinulenta most easily by the shape of the juxta (fig. c21) which is rather short and wide without a narrow projecting apical part. Females have a bursa with four signa and the ductus bursae with a chitinized area near the entrance into the bursa. 38-40 mm.

September to April. Larva (vinulenta of Thaxter); full grown in mid June; dorsum dark olive green, mottled, sides dirty wine color, somewhat mottled; dorsal and subdorsal white lines rather distinct, traces of a white lateral, and a not very strong stigmatal, suffused with purplish; beneath livid red-purple at anterior end.

Massachusetts south to the vicinity of D.C., common at Lakehurst, N.J.; west to Colorado. The race colorado Smith is duller and less red in color.

Hugh McGuinness Hugh McGuinness Hugh McGuinness  Jim Vargo

[ 3 ] -- Eupsilia cirripalea -- 9934 -- Franclemont's Sallow Moth -- [ Text from Forbes 1954 ]

Wing scaling similar to the last, but not quite so striking toward the terminal area. This species is browner than either sidus or vinulenta; the outer margin of the wing is very strikingly crenulate, the teeth almost as pronounced as in the European transversa; in fresh specimens the wings are a deep umber brown, fading to reddish brown; the reniform spot is round and large, and in some specimens a deep fire-orange, as well as white or orange; the lines are more conspicuous than in sidus, the antemedial showing as a wide grayish line in most specimens; the wings are about as broad as in sidus. The male genitalia are immediately distinguishable from sidus and vinulenta by the presence of a large, central, conical process on the juxta, appearing much like a blister in mounts; the female genitalia are distinctive in that they possess only two signa and the ductus bursae has no heavy outstanding chitinizations. 36-40 mm.

[ Line missing in Larva Section ] ....some reticulation on the sides above the ocelli. Cervical shield dark brown with a wide, pale line on each side, this continuing back on the thoracic and abdominal segments as a very faint, narrow, pale subdorsal line on each side. The dorsum of all segments velvety, dark greenish brown, the sides somewhat lighter and with an indication of very vague reticulations; lateral line narrow on the thoracic segments, widening on the abdominal segments, white with a pinkish tint, most intense on last two or three abdominal segments; venter pale yellowish with a strong greenish cast, some pinkish hues below lateral line, most noticeable on thoracic segments. Foodplant: Prunus serotina.

Massachusetts south to the vicinity of Washington, D.C., where it is common, west to Manitoba and Pennsylvania.

James Adams James Adams

[ 4 ] -- Eupsilia vinulenta -- 9933 -- Straight-toothed Sallow Moth -- [ Text from Forbes 1954 ]

Reddish brown, often with strong bluish or purplish shades, especially in the basal area between the antemedial line and base of the wing and in the subterminal and terminal areas, varying considerably in tint, and brighter in the fall than in the spring; the lines much as in the preceding species, but more evident, the antemedial a wide grayish-blue line with a darker brown inner line, the postmedial either light or dark, wide or narrow, often with accompanying dashes on the veins, somewhat sinuous, concave opposite cell and in fold, with slight teeth at M1, M3, Cu1 and Cu2; median shade dark, bent at middle, diffuse and often quite obscure; subterminal line an irregular dark and pale shade; reniform a small elliptical orange, yellow or white spot with white points at upper and lower ends, without the anterior crescent to fill out a normal reniform, or with a slender crescent running before the points, or with one or both points orange or yellow, usually with a gray dot before the lower point. Hind wing mostly fuscous, like the two preceding species, darker than tristigmata. 35-38 mm.

Late September to April. Larva (walkeri of Thaxter) above velvety black with purple shade and some greenish tinges; upper lines hardly visible; stigmatal white, somewhat obliterated at ends; underside bluish green, pinkish at anterior end; head rather broadly edged superiorly with light brown.

Ottawa west to Manitoba, south to the vicinity of Washington, D.C., common at Ithaca, N.Y., Lakehurst, N.J., and Arlington, Va., and south-west to Texas.

Hugh McGuinness Hugh McGuinness Robert Patterson Hugh McGuinness Hugh McGuinness

[ 5 ] -- Eupsilia morrisoni -- 9936 -- Morrison's Sallow Moth -- [ Text from Forbes 1954 ]

Light leather brown, without reddish tint, even when fresh; lines paler and more contrasting, almost perfectly even; the postmedial line a little waved on upper half; subterminal line pale in a slight dark shade, irregularly waved; reniform usually a very narrow pale or pale outline lunule with a small dark spot at lower end. 35-40 mm.

Late September to early May. Larva (Thaxter) mature in early June. Dull blackish with slight bluish green tinge and lateral dull purplish shade, obscurely mottled; lines bluish white, broken, but lateral more complete than dorsal; stigmatal line also bluish white. Tubercles black, ringed with bluish white, the subventrals larger; spiracles black.

Nova Scotia west to Lobo, Ontario; Maine west to Minnesota, south to the District of Columbia and Iowa; commoner in the vicinity of Boston, Massachusetts, than the preceding species.

Hugh McGuinness Larry Line Hugh McGuinness  Jim Vargo

[ 6 ] -- Eupsilia devia -- 9939 -- Lost Sallow Moth -- [ Text from Forbes 1954 ]

Mouse gray, the basal third usually a little paler, frosted with whitish; lines whitish, hardly defined with dark antemedial line the strongest, and sometimes a little diffuse basally, oblique in, and slightly incurved; postmedial line somewhat sinuous, very fine and even; a following broad straight line from costa before apex (at subterminal line) to inner margin halfway between the postmedial and subterminal lines; subterminal line pale, irregular, nearly complete to obsolete. In fresh clean specimens the base, anterior subterminal area and border are a little grayer than the median and outer subterminal areas. Hind wing slightly paler, no red tint. The thoracic crest is higher and outer margins more even than the other species. 30-34 mm.

October to early May. Larva (Thaxter) mature in mid June. Dorsum nearly black, widening at midsegments; subdorsal line inconspicuous except at ends, edged with black; stigmatal broad, whitish with blackish shades, under side light greenish.

Nova Scotia west to British Columbia, south to the vicinity of the District of Columbia and into California in the west. Eupsilia fringata, a western species, is quite similar to devia, but larger and browner, resembling morrisoni in color and devia in pattern; its larva closer to morrisoni, but with a prominent wide purplish white spiracular line.

Robert Patterson  Jim Vargo

[ 7 ] -- Eupsilia new species not yet described
Hugh McGuinness

 Jim Vargo

MothTalk/MothTalk010.htm -- 01/15/2007