Andrena deconstructed: guide to the characters of the DiscoverLife Andrena key

This set of pages is intended as a companion to the DiscoverLife key to Andrena females. The DL key is not for the faint of heart; it contains 100 trait descriptors, and 521 taxa, likely close to the US total. Though daunting, DL is intended for the non-specialist, people that don't have large collections or fluency in the technical language of taxonomists. The key is mainly in plain English. It offers figures and images to explain characters. It is interactive - a user can winnow down the list of possible matches using only characters they can interpret with some confidence.

However: A new user will struggle, until they have spent a hundred hours thinking hard about the characters, looking up the occasional difficult term, and getting it wrong too many times. At least, that has been my experience. What the key - any key - needs is really clear photos that show what a trait condition looks like under a scope. I've been adding these to the DL key, and I repurpose them here, so that I can show them at hi-res [click images to enlarge], and with explanatory comment.

Click any image for a larger magnification.

Related taxonomy pages

Glossary of bee terms
Key to Andrena subgenera of the PNW
Endangered plants of the PNW
Key to Lasioglossum of the PPP
Photo blog, 2024, 2025

Navigation:

Diagnoses using the DL Guide:

1) Vertex - the top of the head, above the ocelli

Vertex height (or length) is the distance between a lateral ocellus and the posterior edge of the head. The good thing about this character is that it is always visible, though it is difficult to gauge accurately, even with a reticle.

Vertex height of 1 ocellar diameter. Image also shows 1 OD distance from the fovea.

Short vertex, < 1 OD.

Tall vertex, nearly 2OD.

2) Antenna, particularly first vs second+third flagellar segments

The first flagellar segment here is about equal in length to the second+third.

F1 longer than F1+F2. Image below is A. erythronii.

3) Fovea: the areas of depressed hairs medial to the eye

Super important as characters for female Andrena. Tricky to assess for degraded specimens, where facial hairs obscure the fovea, or in poor light. Move the light, move the specimen, trim the hairs. If the fovea are hairless ... perhaps you have a Panurginus.

Fovea dark; length to lower level of antennal socket.

Fovea light; width about equal to antennal socket;length nearly to top of clypeus.

Fovea narrow, less than width of antennal socket.

Fovea dark, narrow, less than width of antennal socket, AND closer than its own width from the eye margin.

Fovea narrow, less than width of antennal socket, AND distant by greater than its own width from the eye margin.

Fovea moderately impressed; <1 ocellar diameter from ocellus.

Fovea is shallow. Dark above, pale below.

Fovea is deeply impressed; color: pale.

4) Clypeus - the face below the antennal sockets

There are two key traits here. Is the surface texture shiny, roughened, or a both? Is there a an impunctate medial space?

Surface texture completely dulled.

The surface texture here transitions from relatively smooth medially to somewhat tesselate ("tiled") laterally. Punctation is sparse.

Surface texture shiny medially, dull at edges; distinct impunctate medial band.

Shiny; impunctate band; punctures coarse and deep.

Shiny/dull; impunctate band. Also: clypeus flat. This was so evident that I wondered if it was unusual. In DL, I find that there are only 2 Andrena species with this trait. This one is erythronii.

5) Malar space: the distance between the eye rim and mandible base.

In the DL key, the short malar spaces are described in relation to the eye rim. This the literal rim, not including the band of darker ommatidia. Large malar spaces are described in terms of L x W.

Short: less than eye rim

Short, but greater than eye rim.

Long, about 1/5 as long as broad.

Long, about 1/3 as long as broad.

6) Labral Process: a projection immediately below the clypeus.

The characters in DiscoverLife concern length (compared to the labrum) and shape of the margin. The tricky calls here are deciding the boundaries between weakly, emarginate, and bidentate. DL indicates 194 species that might have an entire process. But just 44 that are scored for only having this condition. My suspicion is that DL scores are broad in order to allow for misinterpretation (rather than reflecting within-species variation).

Entire, broadly truncate; long

Slightly emarginate. Note strong transverse ridges. A. erythronii.

Emarginate, but not bidentate.

Emarginate. Sam Droege tip: viewed frontally this will appear entire; tipped back, the indentation is visible.

Bidentate.

Entire, strap-like (A. barbilabris)

Labrum, crista and sulcus

If you are well beyond DiscoverLife, and puzzling over the primary literature, you will encounter features of the labrum. This lies immediately beneath the labral process. It may feature a median crista (ridge), and/or sulcus (trough), and additional ornamentation (lamellae). These are difficult to interpret, as the labrum is usually obscured by overlying hairs.

Median crista of labrum.

7) Pronotum: Surface between mesepisternum and head; "neck."

There are two important characters, particularly useful in discriminating subgenera. The humeral angle is akin to the shoulder when viewed from in front. The pronotal ridge is a "ridge extending down from humeral angle." These pronotal characters are difficult to evaluate, often obscured from clear view by the head and hairs. Removing heads of low quality specimens is a good approach to understanding this character.

Photo at right: Andrena nivalis, specimen determined by LeBerge. The humeral angle is akin to shoulder when viewed from in front. From the side, as in this image, it is difficult to judge, but the angle is absent (or weak). There is a discernible crease on the pronotum in this image. It is NOT a pronotal ridge - it does not extend down from the humeral angle. Note from Joel Gardner, who explained this to me:

[The lateral sulcus] is present on almost all species that lack a pronotal ridge, Scaphandrena being the main exception (the absence of the lateral sulcus is a good way to recognize certain Scaphandrena). Most species that have a pronotal ridge lack a lateral sulcus, "Tylandrena" (in the classical sense) being the main exception.

Where to look for pronotum features.

This is a pronounced humeral angle.

Pronotum lacking a humeral angle.

Pronotal ridge absent.

Pronotal ridge present. As noted, taxa with this feature will usually lack a lateral sulcus.

Pronotum with distinct ridge AND "deeply impressed diagonal suture."

8) Scutum: Dorsal area between wings

The DL key asks you to assess pit density "between the parapsidal lines, except midline," and surface texture.

Pits 1-3 widths apart. Shows minimal shiny area posteriorally (left).

Pits ~3 widths apart; surface roughened/"dull."

Pits > 3 widths apart. Rough/tessalate and shinier areas both evident.

9) Propodeum: Posterior thorax, facing the abdomen, with a roughly triangular enclosure posterior to the scutellum

Caption for Image

Triangle 100% sculptured. Posterior and lateral borders with definite ridge or carina. A. sigmundi.

Also 100% sculptured, but carina absent. Surface outside of triangle is rugose. A. crataegi.

Again, 100% in triangle. No carina. Texture outside triangle "Coarsely and irregularly roughened."

Sculpturing limited to about 20%, on the dorsal edge of triangle. Surface outside triangle is "areolate."

Sculpturing limited to about 10-20%, on the dorsal edge of triangle. No carina. Surface outside triangle is "areolate."

Sculpturing about 10%. A. nivalis.

10) Wing.

The less common traits - short r-vein or 2 submarginal cells - will narrow possibilities considerably. The vein m-cu trait is less useful - many Andrena species in DL are scored very broadly for this trait.

80% of species have 3 submarginal cells.

Less common: 2 submarginal cells.

Upper arrow is the r vein, which is long - length = 4 vein widths. Lower arrow is the position at which vein m-cu meets the second submarginal cell. In this case, ~3/4 of the way distal to the base of the cell.

Compare to left; r vein is short, < 4 vein widths. Vein m-cu meets second SMC ~2-3 of the way distal to the base of the cell.

11) Corbicula: Pollen carrying area lateral to the propodeum.

Complete corbicula

Complete corbicula, with anterior fringe of hairs, and bare interior.

Hairless interior.

An incomplete corbicula, lacking an anterior fringe. Typically these will also have internal hairs.

Left: weak anterior fringe; Right: internal hairs.

12) Pygidial plate: Hairless protrusion from tergum 6.

The pygidial plate is a sort of spatula with which bees prepare brood cells. DL differentiates two conditions, "with an internal plate or ridge," or "unmodified." Modified plates appear to take many forms, are no doubt useful ID clues, beyond DL.

13) Hind leg, trochanteral flocculus.

The curly hairs: a complete flocculus. A. barbilabris.

Complete flocculus.

An incomplete flocculus, hairs straighter, and short.

14) Hind tibia: shape

Tricky, because hairs tend to obscure the actual edges of the underlying integument. Best to view with back-light.

Narrow, nearly parallel-sided, scarcely broader at apex than at midpoint.

Normal, broader at apex than at midpoint, but at most 1.5 times as wide as basitarsus.

Cuneate, apex at least 1.5 times as wide as basitarsus.

14) Hind tibia: scopal hair formation

Hairs simple and unbranched

The hairs are so dense you may be tempted to assume plumose. But they are simple. A. erythronii.

Weakly branched throughout.

Plumose, with many branches.

Plumose, with no room for doubt.

15) Hind tibial spurs

These might deviate in several ways from the typical straight or gently curved condition. DL presents 5 options, that require interpreting "slight but obviously," "sometimes twisted," "distinctly." In the absence of clarity on this, I can only follow DL: if I have a known species, I will assume that it is correctly scored.

Normal, straight.

"Strongly bent at least in outer half AND broadened and flattened near base"

A variation on "Strongly bent at least in outer half AND broadened and flattened near base"

Twisted spur of A. barbilabris.

Hooked.

Diagnoses using the DL Guide:

Andrena erythronii (Leucandrena)

Easy calls, based on images at right:

Michigan, 11mm, April;
Clypeus shiny/dull;
Weakly emarginate labral process;
F1>F2+F3;

Complete corbicula;

Tibial hairs simple, pale, long;
T2 granular surface;
Propodeal triangle ~20% scupltured

Initial result:

A. barbara
A. erythronii
A. thaspii

Notable: Abundantly hairy. Integument dark--more black than brown. Complete corbicula. 11 mm length.

A priori, I believe this is A. erythronii. One, because it was collected in the vicinity of trout lily, a typical associate. Two, because this was suggested on iNat by Max McCarthy. Three, because a single unusual trait--flattened clypeus--is seen in MI only for A. erythronii and A. accepta (easily rejected).

In any case, I get A. erythronii and just two alternatives with the basic traits listed at left. Rule out A. barbara: "Pits on basal area of T2 distinct and crowded, separated by FAR less than 1 pit width ..." Rule out A. thaspii: "Labral process BIDENTATE."

So far so good: erythronii. However, DL can easily take me down a different path, if I choose trait conditions that I see in these images, that DL does not assign for A. erythronii. One is the faint but definite pitting on T2. However DL (and LaBerge) indicate an impunctate T2. Two, I see a nearly complete hair band on T2; DL scores erythronii as having broadly interrupted, or no T2 band, LaBerge says: "terga 2-4 with weak apical pale fasciae interrupted medially on terga 2 and 3."

If I have A. erythronii here, DL would probably fail to get a diagnosis. If this is NOT erythronii, DL can't say what it actually is.

Clypeus shiny, with wide impunctate band. Key: the central disk is flattened (confirmed with side view). True for only two MI species (if I choose "only" in the HAS menu option)

Clypeus shiny, with wide impunctate band. Key: the central disk is flattened (confirmed with side view).

Propodeal triangle, weakly sculptured.

T2 surface dull. Punctate? Hair band? See discussion.

Tibial hairs are lush, but simple.

Andrena wilkella (Taeniandrena)

Easy calls, based on 1st 3 images at right:

Michigan, 11mm, April;
Clypeus dull;
F1=F2+F3;
vertex 1 ocd;

Incomplete corbicula;

Tibial hairs simple, pale;
T2 bands narrowly interrupted; pitting dense;
Fovea dark abve;
Scutum dull, pitting dense;
Propodeal triangle 50%;

Initial result:

A. cressonii
A. brevipalpis
A. wilkella

Notable: All light/tawny-orange hairs. Dense, orange scutal hairs. Malar area short. Gena narrow. Vertex> 1ocd. Long unbranched tibial hairs. Triangle roughened, not rugose.

There is no path in DL that clearly excludes species other than A. wilkella. So I looked at the primary literature: A Revision of the Bees of the Genus Andrena of the Western Hemisphere. Part XIII. Subgenera Simandrena and Taeniandrena (LaBerge, 1989)

"A large, readily recognized bee from North eastern North America. The female has slightly elongated punctures on the flattened clypeus, highly punctate metasomal terga, roug ened but not rugulate propodeal enclosure ..."

Clypeus notably flat. Punctures elongate (I think). Clincher: "Labral process tra ezoidal, slightly constricted before apex, emarginate apically, surface basad of apical teeth with fine curved rugulae, shiny;" The latter - rugulae - is clear here.

Andrena wilkella / cressonii ?

See preceding wilkella diagnosis. The same traits apply. But evaluate wilkella vs cressonii:

T2 surface: granular for wilkella, shiny for cressonii;
Compare labral process images. Short and broadly truncate in this specimen.

Either of these conditions will narrow the result to A. cressonii, not wilkella. In fact, the summary description by Joel Gardner (on DL page) says this for A. cressonii: "is very easily recognized by ... the extremely short and wide labral process, and the shiny tergum with distinct, crowded punctures." IF this is cressonii, DiscoverLife gets me there. IF this is wilkella, I would misdiagnose.

Notable: Dead ringer for A. wilkella preceding, except for shining tergae, which are very clear in this image and on closer examination.

Dead ringer for A. wilkella preceding.

cressonii-like labral process. Rounder clypeal punctures?

Andrena wilkella male (Taeniandrena)

Easy calls:

Michigan, 8mm, June;
Clypeus shiny/dull;
Emarginate labral process;

Dark clypeus/paraocular area;

Propodeal triangle 50% sculptured;
T2 bands broadly interrupted; pitting indistinct; granular T2
Clypeal hairs sparse, pitting 1-3;
Vertex greater than 1-1.5 ocd.

Initial result:

A. chippewaensis
A. fulgida
A. geranii
BUT NOT A. wilkella

The trait conditions of A. wilkella SHOULD in fact appear among matches (when checked against the menu in DL). I.e., DL yields a false negative this case.

Notable: Tergae, scutum, head densely hairy.
T2: A. wilkella is scored as having dense pits, separated by less than one pit diameter. I would have called the very shallow pits here "indistinct."

There

Two specimens that strike me as having the same vibe.

Discussion: I disagree with DL about this ID, based on examination of several specimens determined by J.S. Ascher. The DL scoring is accurate, but the matching algorithm is off. This kind of mistake is surprisingly uncommon in my experience, given the complexity of a key for 521 species.

Andrena placata (Callandrena)

Easy calls:

Michigan, 10mm, August;
Clypeus dull;
Labral process bidentate;

Incomplete corbicula;

Tibial hairs simple;
T2 bands complete; pitting 1-3;
Fovea dark abve;
Propodeum 50-80%

Initial result:

A. gardineri
A. placata
A. wilkella

Evidence against A. wilkella: this specimen with plumose tibial scopa (simple in wilkella); absent impuncate center of clypeus (present in wilkella).
A. placata feature: "Terga 5 and 6 hairs usually dark brown."

Above: Medial impunctate band of clypeus absent; A. wilkella would have this condition.
Below: Distinctly bidentate labral process.

Above:Highly plumose tibial scopa; simple in wilkella.
Below:Of the three options, only A. placata has the middle leg basitatsus "expanded medially, broader than hind basitarsus.""

Andrena imitatrix (Scrapteropsis)

Easy calls, based on 1st 3 images at right:

Michigan, 10mm;
Clypeus shiny/dull;

Triangle 100%;

Scutum w/ dense pitting;
T2 bands broadly interrupted;
T2 shiny, pit spacing 1-3.

Initial result:

Andrena alleghaniensis
Andrena imitatrix
Andrena morrisonella

Note on image: not clear here that clypeus is shiny in center. But it is.

Fovea broader than antennal socket: excludes A. alleghaniensis. Also: alleghaniensis with short scutal hairs.

Above: Labral process emarginate [alleghaniensis bidentate, morrisonella entire or weak].
Below: "Propodeal corbicula hairs in anterior half mostly or entirely branched [simple in morrisonella].

Andrena carlini (Melandrena)

Easy calls, based on 2 images at right:

Michigan, 13mm;
Clypeus shiny/dull;
Median impunctate band wide (vs vicina);

Scopal and cheek hairs dark;

Complete corbicula;
Scutm hair long; thorax pale above, dark below;
Metasomal hairs dark; hair bands absent.

Initial result:

Andrena carlini
Andrena milwaukeensis
Andrena thaspii
Andrena vicina

Above: Vertex=2ocd. Excludes milwaukeensis and thaspii.
Below: Very short malar space. Only matches to A. vicina.

Andrena crataegi (Plastandrena)

Easy calls:

Oregon, 12mm;
Clypeus shiny/dull;

Triangle 100%;

Incomplete corbicula;
T2 pitting dense;
Simple scopal hairs;
Scutum shiny.

Initial result:

Andrena amphibola
Andrena crataegi

A. amphiloba does not match. We would expect dark hairs on the tibia, a normal tibial spur, and a fovea like Trachandrena.

Above: "Noted for coarse propodeum and curved and thickened inner hind tibial spur."
Below: Distinctive carinate ridge of hind femur--a crataegi thing.

Andrena salicifloris (Trachandrena)

Easy calls:

Oregon, 12mm;
Clypeus shiny, impunctate midline;

Triangle 100%, with enclosing carina;

Incomplete corbicula;
T2 pit spacing 1-3;
Pale scopal hairs;
Scutum with dense pitting;

Initial result:

Andrena fuscicauda
Andrena miranda
Andrena salicifloris

All matches are subgenus Trachandrena, characterized coarse sculpturing, an entirely rugose, enclosed propodeum, and fovea narrowed at the level of the antennal socket. DL does not unamnbiguously resolve species. So I consulted A Revision of the Bees of the Genus Andrena of the Western Hemisphere. Part VI. Subgenus Trachandrena (LaBerge). A. fuscicauda doesn't match this specimen in several respects. Differentiating miranda and salicifloris is harder.

miranda vs salicifloris: A. salcifloris and A. miranda split on a final couplet. A. salicifloris: mesoscutum with anterior third with punctures crowded, separated by mere ridges; vertex above lateral ocellus equals about one ocellar diameter.
A. miranda: Mesoscutum with anterior third with punctures discrete, separated by half to almost one puncture width; vertex above lateral ocellus usually distinctly longer than one ocellar diameter.
My specimen appears to have crowded punctures AND a long vertex. To quote LaBerge: "There is no doubt that misidentification of such specimens will continue and, indeed, it is often impossible to place some in the correct species with any confidence."

Above: Marrow lower fovea of Trachandrena.
Below: Scutum of another specimen.

Andrena forbesii (Trachandrena)

Easy calls:

Michigan, 10-12mm;
Clypeus shiny, impunctate midline;

Triangle 100%, with enclosing carina;

Propodeum outside triangle roughly irregular;
Incomplete corbicula;
Hair bands absent;
Pale scopal hairs;
Scutum pitting sparser than in A. salicifloris;
Scutum texture dull;

Initial result:

Andrena sigmundi
Andrena miranda
Andrena rugosa

All matches are subgenus Trachandrena, as described for A. salicifloris above. The list does not include A. forbesii, so I take issue with DL. My support for the A. forbesii diagnosis: 100 specimens from the Rufus Isaacs lab, many with J. Ascher dets.

Below: DL scores A. forbesii with ocellus-fovea distance greater than 1 od. In this pic, and close-up at right, the distance appears less than 1 od. If I ignore the DL score for fovea-ocellus distance, A. forbesii matches in DL.

Above: Clypeal impunctate medial line indistinct. Crowded punctures below ocelli, and weak rugulae. Also, normal hind tibial spurs--excludes A. sigmundi.

Above: Not miranda, described as unique among this group with "Propodeum with triangle without ridged sides, boundaries indistinct, adjacent areas often sculptured nearly as coarsely as triangle." My specimens: "propodeum distinctly finer outside than inside triangle" A. miranda or A. rugosa would also have tergum 2 with depressed apical area occupying three-fourths or more of midline" (about half for my specimens).

DL comments specific to A. forbesii: Face below ocelli duller than parocular area, with weak rugulae longitudinal or lacking, with punctures separated mostly by 0.5 puncture widths or less - Vertex above lateral ocelli equals 1.5 ocellar diameters or slightly less - Scutum hairs normal, long, erect, usually slender

Andrena nasonii (Simandrena)

Easy calls:

Michigan, 8mm;
Clypeus dull;

Triangle 100%;

Complete corbicula;
Hind tibia cuneate, hairs short and simple;
Wing vein r short.

Result: Andrena nasonii

Above: Propodeal triangle 100% sculptured; note posterior view of corbicula.
Below: Cuneate hind tibia.

Above: Tubercle on the posterolateral edge of the mesepisternum: a nasonii thing.
Below: Same feature on male A. nasonii.

Andrena pallidofovea (Simandrena)

Easy calls:

Nevada, 9mm, June;
Clypeus dull;

labral process entire and long;

vertex longer than 1-1.5 od;

Fovea more than 1 od from ocellus;

Complete corbicula;
Hind tibia cuneate, hairs pale and weakly branched;
T2 granular;

T2 hair band narrowly interrupted;

Result: Andrena pallidofovea

Below: Fovea long, malar space short, clypeal hairs plumose.

Andrena chlorogaster (Micrandrena)

Easy calls:

Oregon, 7mm;
Clypeus dull;
Integument metallic;

T2 pits absent, granular surface;

Pale hair bands, hairs pale,
Labral process entire;
Propodeal sculpturing 50+%;
Metasomal hair bands absent;
Corbicula incomplete.

Result: Andrena chlorogaster. A second approach, given subgenus Micrandrena: consult key by Ribble. A. chlorogaster is consistent.

Andrena pensilis (Simandrena)

Easy calls:

Oregon, 10mm;
Clypeus dull, without median band, flat in profile;
Maxillary palpus exceeds galea by two palpal segments;

Fovea dark above, light below;

Malar space extremely short;
Labral process entire;
Vertex ~1 ocd;
Pygidial plate w/ raised triangle;

Result: Andrena pensilis.

I note that DL scores A. pensilis as having the first flagellomere as "Longer than second flagellomere but not as long as second plus third." In my specimen images, the first flagellomere IS longer than F2+F3. So we disagree, but I stand by my diagnosis--the clypeal hairs are the clincher here.

LaBerege: Andrena pensilis is a California species that is readily recognized in the female sex by the long, relative simple, tapering clypeal hairs, which are wavy distally. IN A revision of the bees of the genus Andrena of the Western Hemisphere. Part XIII. Subgenera Simandrena and Taeniandrena.

Male Andrena carolina (Andrena s. str.)

Easy calls:

Michigan, 8mm;
Clypeus hairs sparse; unpitted midline, pits spaced 1-3

Mandibles distinctly decussate, with weak tooth;

Labral process emarginate;
Cheek 2X eye width;
Metasomal hair bands absent;
F1 longer than F2, but not F2+3.

Initial result:

Andrena carolina
Andrena chippewaensis
Andrena fulgida

These 3 species cannot be distinguished in DL. A. carolina is far more abundant, and associated with blueberries, likely the case for this specimen.

Quadrangle longer than broad. Tawny hairs. Clypeus shiny-dull, punctate except midline. Decussate mandibles. Max palp exceeds galea by 2 segments.

Cheek 2X as wide as eye. From DL: With distinct angle of 90 degrees or more along lower rear margin breaking the curve from top to bottom.

Above, from DL: UNCOMMON: With longitudinal rugulae in basal half, tessellate or smooth at apex
Below, from DL: DL: weak tooth not projecting below level of mandible articulation.

Andrena auricoma (Ptilandrena)

Easy calls:

Oregon, 9mm;
Clypeus dull;
labral process emarginate;

Triangle 0% sculptured;

Incomplete corbicula;
Complete hair bands;
T2 pitting 1-3;
Cuneate tibia;
Pale scopal hairs;

The overall orange coloration is notable, as is the resemblance to A. astragali, another Ptilandrena.

Initial result:

Andrena auricoma
Andrena bucculenta
Andrena lutehirta

DL has no images of bucculenta or lutehirta, so overall appearance is unhelpful. A. lutehirta is scored as having a long vertex (1.5-2od), whereas this specimen has vertex less than one ocellar diameter. This specimen has 3 SMC, whereas A. bucculenta is scored as having 2SMC, a condition that excludes the subgenus of the other two options. This leaves a diagnosis of A. auricoma.

Above: An 88 year old specimen from OSU. Note cuneate tibia.
Below: The sculpturing here is 0% sculptured, although the surface texture is borderline. The label here indicates Euandrena. But Ptilandrena is the updated classification.

Cautionary notes: Scoring for western Andrena species is often incomplete.

The LaBerge subgenus key would seem to indicate Ptilandrena as having highly plumose tibial scopae, whereas this specimen has simple hairs. However LaBerge himself contradicts this: I have images of a specimen, with det. by LaBerge, of another Ptilandrena (A. nigrihirta) with tibial scopa very similar to this specimen, with simple hairs.

Above: Slightly emarginate labral process.
Below: Note super-shiny tergae, sculpturing of frons.

Andrena astragali (Ptilandrena)

Shortcut: Andrena astragali forages exclusively on death camas, which is visited by no other bee.

Version 5 Dec 2024. All text and photos David Cappaert, with the advice of Cody Blackketter and Marisa Fisher of Quamash EcoResearch. I grant permission for any non-commercial use of text and images. See also: Key to the Andrena subgenera (females) of the Pacific Northwest. cappaert@comcast.net