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Megachile fortis Cresson, 1872
Megachile emoryi Cockerell, 1904; Megachile fortis var vestali Cockerell, 1913; Megachile (Xanthosarus) fortis Cresson, 1872

Life   Insecta   Hymenoptera   Apoidea   Megachilidae   Megachile
Subgenus: Phaenosarus

Megachile fortis, female, face
Smithsonian Institution, Entomology Department · 9
Megachile fortis, female, face

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Megachile fortis, female, side
Smithsonian Institution, Entomology Department · 9
Megachile fortis, female, side
Megachile fortis, female, top
Smithsonian Institution, Entomology Department · 9
Megachile fortis, female, top

Megachile fortis, female, wing
Smithsonian Institution, Entomology Department · 9
Megachile fortis, female, wing
Megachile fortis, male, face
Smithsonian Institution, Entomology Department · 9
Megachile fortis, male, face

Megachile fortis, male, side
Smithsonian Institution, Entomology Department · 9
Megachile fortis, male, side
Megachile fortis, male, top
Smithsonian Institution, Entomology Department · 9
Megachile fortis, male, top

Megachile fortis, male, wing
Smithsonian Institution, Entomology Department · 9
Megachile fortis, male, wing
Megachile fortis FEM mm x ZS PMax
© Copyright Laurence Packer 2014 · 7
Megachile fortis FEM mm x ZS PMax

Megachile fortis, U, face, Jackson County, South Dakota ---.. ZS PMax
© Copyright source/photographer · 5
Megachile fortis, U, face, Jackson County, South Dakota ---.. ZS PMax
Megachile fortis, U, side, Jackson County, South Dakota ---.. ZS PMax
© Copyright source/photographer · 5
Megachile fortis, U, side, Jackson County, South Dakota ---.. ZS PMax

Megachile fortis
Jelle Devalez · 1
Megachile fortis
Megachile fortis, female, mandible, 5 toothed
© USDA Bee Biology and Systematics Laboratory, Logan Utah · 1
Megachile fortis, female, mandible, 5 toothed

Megachile fortis, male, s4 with small median projection
© USDA Bee Biology and Systematics Laboratory, Logan Utah · 1
Megachile fortis, male, s4 with small median projection
Megachile fortis, female, mandibles
© NC Agriculture State Experiment Station Technical Bulletin Number 152, T. B. Mitchell, 1962 · 1
Megachile fortis, female, mandibles
Overview
Reprinted with permission from: Mitchell, T.B. 1962 Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 152.


FEMALE—Length 16-18 mm.; entirely black, including tegulae and legs, spurs brownish-testaceous; eyes parallel, clypeal margin straight, with a few minute irregularities; mandibles 5-dentate as shown, (fig. 51) lateral ocelli considerably nearer eyes than to margin of vertex; cheeks subequal to eyes in width; vertex and cheeks very finely and closely punctate throughout, and face below ocelli rather finely and closely punctate, the supraclypeal area more densely rugose, elypeus finely and densely punctate along upper margin, but punctures becoming more coarse, deep and distinct and at least slightly separated toward apical margin; pubescence of head and thorax entirely pale, rather short and quite dense, pale yellowish around antennae and sides of face, more whitish on cheeks below, becoming thin and more yellowish above, that on vertex rather short but erect, quite copious, largely pale yellow; pleura and posterior face of propodeum with quite dense, rather short, pale yellowish pubescence, that on dorsum of thorax somewhat brighter yellow, rather short but copious, partially decumbent on scutum; thorax very dull, uniformly very densely and finely rugosopunctate, propodeum somewhat more shining laterally, posterior face dull, with minute, shallow, close and vague punctures; basitarsi only slightly shorter than their respective tibiae, mid and hind pair nearly as broad as their tibiae, tegulae somewhat shining, but with exceedingly minute and very close punctures; wings subhyaline, very faintly clouded apically, veins piceous; abdominal terga 2 and quite deeply grooved across base, basal margin of groove quite distinctly carinate, 4 shallowly depressed across base but hardly grooved, apical margins of all terga somewhat depressed, yellowish-hyaline, densely fringed with short, yellowish pubescence forming conspicuous, transverse and entire fasciae; discal pubescence of tergum 1 copious, elongate pale yellow, that on 2 somewhat shorter, and very short and less conspicuous on 3-5; punctures very fine and quite densely crowded, uniform the more basal terga, becoming slightly coarser toward apical margin of 5, this hardly all depressed across base and without a definite, basal, carina-like margin; tergum 6nearly straight in profile, with only a very few, short, erect hairs toward the base visible, punctures across base in dorsal view very fine, densely crowded but rather distinct, becoming indistinct apically, apical half covered with yellowish, appressed hairs which obscure the surface; sternum 6 rather uniformly covered with pale, rather short, scopal hairs, apical margin with a rather prominant, thickened margin, beyond which there is a dense fringe of very short, yellowish hairs, scopa otherwise pale yellow; sternal plates closely punctate, sternal fasciae not evident.

MALE—Length 14-15 mm.; black, tegulae somewhat more brownish-piceous, mid and hind legs black, anterior tarsi yellow, and front tibiae and femora in part pale in color; eyes parallel; clypeal margin nearly straight beneath a dense beard; mandibles 3-dentate (fig. 51), inferior process extremely broad, terminating below at an acute angle near base, but separated from apical part by a very broadly rounded emarginate area, lower margin less oblique; apical segment of flagellum very broadly dilated; lateral ocelli considerably nearer eyes than to margin of vertex; cheeks very slightly broader than eyes, obscurely angulate and slightly excavated, below, this area fringed with dense, yellowish, rather short hairs; vertex and cheeks quite uniformly, finely and densely punctate, lower portions of face in large part very finely and closely punctate beneath dense pubescence which completely hides surface; pubescence of face and vertex yellowish, dense below level of antennae, rather elongate on vertex medially, becoming shorter, more inconspicuous laterally, very thin and short on cheeks, becoming somewhat paler and more dense along inferior margin; pubescence of thorax rather dense, not very elongate, pale yellowish on pleura and propodeum, somewhat deeper yellow and rather short and erect but not hiding surface on dorsum of thorax; scutum and scutellum dull, with very fine, densely crowded punctures, those on pleura minute and densely crowded; lateral faces of propodeum somewhat more shining, obscurely punctate, posterior face somewhat less shining, with close but rather vague and indistinct punctures; anterior coxal spines robust, rather acutely pointed apically, broad at base, with a large transverse patch of suberect, ferruginous bristles at base, coxae otherwise largely bare; front tarsi pale yellow, rather broadly dilated, about equal to the tibiae, but anterior margin only very obscurely excavated, posterior fringe dense, about equal in length to breadth of the segments, whitish toward apical segments, more brownish-testaceous at base; outer face of front tibiae piceous, with tip yellowish, other two faces moreferruginous, and posterior face of front femora piceous, with lower margin carinate and testaceous, other faces largely testaceous, densely fringed posteriorly with yellowish hairs which are elongate toward base; mid tibial spurs well developed; basitarsi slightly narrower, considerably shorter than their tibiae, with a much elongated, yellowish, posterior fringe, hind femora somewhat swollen, hind basitarsi about half the length of their tibiae; tegulae very minutely and closely punctate, anterior part quite densely pubescent; terga 2 and 3 quite deeply depressed at base, 4 and 5 more shallowly so, basal margin of depressions distinct, more or less carinate, apical margins of terga uniformly, rather deeply depressed, very deeply so on 4 and 5, the discs overhanging the depressed rims, with dense, entire, yellowish, apical fasciae on all, basal tergum with copious, elongate, yellowish pubescence, apical fringe rather obscure, discal pubescence of the following terga erect, conspicuous, entirely pale, but not obscuring the fasciae; tergum 5 more or less bare apically, punctures very fine and close throughout, minute on the more basal terga, becoming somewhat more irregular and substriate on 5 apically, 6 rather densely tomentose, very closely and finely punctate beneath the pubescence, with a slight median ridge, and slightly depressed on each side, the carina slightly downcurved and truncate, with no median emargination, median apical teeth broadly carinate, much nearer the very small lateral angles than to each other; tergum 7 obscurely angulate medially; sterna 1-4 exposed, very finely, uniformly and closely punctate, apical margins depressed, yellowish-hyaline, quite densely fasciate, the fasciate fringes much broader laterally, sternum 4 not conspicuously fringed but with a quite distinct, median, carinate and acute tubercle; sternum 5 with lateral, apical pubescent plates distinct from the lateral and basal sclerotized areas and the median setose area, this broad apically, narrowed basally, separated from basal margin of plate by a membraneous area, setae robust, abruptly dilated at tips (fig. 46); sternum 6 with broad, more or less oblique setose areas that are well separated medially, lateral portions of plate long pubescent, apical lobe short, but lateral angles produced into long, slender projections; gonocoxites robust, narrowed above base, slightly sinuate, flexed ventrally near apex which is dilated, compressed, bearing long conspicuous setae (fig. 50).DISTRIBUTION—South Dakota to New Mexico, east to Texas and Illinois, July and August. The occurrence of fortis in Illinois was shown by the collection of two specimens on August 20, 1957, a male at Bishop-ville, Mason Co., and a female at Mason State Forest, on Helianthus (Mitchell)

FLOWER RECORDS — Dicrophyllum, Helianthus, Silphium, Solidago and Vernonia.

Kinds
Extracted from: Sheffield C. S., et al (2011). Leaf cutter and Mason Bees of the Genus Megachile Latreille (Hymenoptera; Megachilidae) in Canada and Alaska. Canadian Journal of Arthropod Identification No. 18

Megachile (Xanthosarus) fortis Cresson, 1872

Megachile fortis Cresson, 1872. Trans. Amer. Entomol. Soc. 4: 262 (♂). Megachile emoryi Cockerell, 1904. Entomologist 37: 7 (♀). Megachile fortis var. vestali Cockerell, 1913. Ann. Mag. Nat. Hist. (8) 11: 530 (♂).

Diagnosis. The female of M. fortis can be recognized by the combination of 5-dentate mandibles, with the 4th tooth approximately parallel-sided throughout its length, with an oblique emargination between 3rd and 4th teeth which is much deeper than emargination between 2nd and 3rd teeth, the width of emargination between the 3rd and 4th teeth broadly semi-circular in shape, the apical border of S6 being thickened and weakly upcurved, extending slightly beyond the apical tergum. They are most similar to M. dentitarsus, M. latimanus and M. perihirta. Females of these species have the width of emargination between 3rd and 4th teeth subequal or at most twice as wide as the 4th tooth at midlength, the emargination tapering and angled towards inner mandibular edge, and S6 with apical border not thickened or upcurved, not extending beyond apical margin of T6. The male of M. fortis is distinct from all other Megachile by the truncate, basal mandibular tooth. In addition, and like males of the subgenus Megachiloides, the postmedian transverse carina on T6 is rounded or obtusely angulate medially (not deeply emarginate as in other Xanthosarus).

FEMALE: Length 16-18 mm.

Head. 1) compound eyes parallel; lateral ocelli nearer eyes than margin of vertex (4:5), 2) apical rim of clypeus shiny and impunctate, slightly incurved medially, with a few minute crenulations laterally, 3) mandibles 5-dentate, width of emargination between 3rd and 4th teeth about three times as great as the width of the 4th tooth at midlength, shallow but distinct emargination between 4th and 5th teeth, with complete cutting edges between 3rd and 4th and 4th and 5th teeth, and an incomplete one between the 2nd and 3rd teeth (Plate 1, Figure M33), 4) gena subequal to compound eye in width, 5) vertex and gena very finely and closely punctate throughout, frons rather finely and closely punctate, the supraclypeal area more densely rugose, clypeus finely and densely punctate along upper margin with an incomplete median impunctate line basally, but punctures becoming more coarse, deep and distinct and at least slightly separated toward apical margin, 6) pubescence of head entirely pale yellowish, rather short and quite dense around antennae and paraocular area, more whitish and elongate on gena below, becoming sparse and more yellowish above, that on vertex rather short but erect, 7) F1 longer than broad (3:2), longer than pedicel, subequal in length to remaining flagellomeres, apical flagellomere more elongate (5.5:2).

Mesosoma. 1) pubescence entirely pale, pleura and posterior face of propodeum with quite dense, rather short, pale yellowish pubescence, that on dorsal surface somewhat brighter yellow, rather short but copious, partially decumbent medially on mesoscutum, 2) surface very dull, uniformly very densely and finely rugosopunctate, propodeum somewhat more shining laterally, with minute, shallow, close and vague punctures, triangle dull and impunctate, 3) basitarsi only slightly shorter than their tibiae, mid and hind basitarsi nearly as broad as their tibiae, spurs yellowish-brown, 4) tegula somewhat shining, with exceedingly minute and very close punctures, pubescent anteriorly, 5) wings subhyaline, very faintly clouded apically, veins black.

Metasoma. 1) T2 and T3 quite deeply grooved across base, basal margin of groove quite distinctly carinate, T4 shallowly depressed across base but hardly grooved, T5 hardly depressed across base and without a definite, basal, carina-like margin, apical margins of T1-T5 somewhat depressed, yellowish-hyaline, densely fringed with short, yellowish pubescence forming conspicuous, transverse and entire fasciae; discal pubescence of T1 copious, elongate, pale yellow, that on T2 somewhat shorter, and very short and less conspicuous on T3-T5; punctures very fine and quite densely crowded, uniform on the more basal terga, becoming slightly coarser toward apical margin of T5, T6 nearly straight in profile, with only a very few, short, erect hairs toward the base, T6 with punctures across base very fine, densely crowded but rather distinct, becoming indistinct apically, apical half covered with yellowish, appressed hairs that obscure the surface, 2) S6 rather uniformly covered with pale, rather short, scopal hairs, apically with a rather prominent, thickened margin that is bare, weakly up curved and extending a little beyond the apical tergum, scopa otherwise pale yellow; sternal plates closely punctate.

MALE: Length 14-15 mm.

Head. 1) compound eyes parallel; lateral ocelli considerably nearer eyes than margin of vertex (7:5), 2) clypeal margin nearly straight beneath dense pubescence, with a small, median shiny protuberance, 3) mandibles 3-dentate, lower process extremely broad, truncate, basal in position, 4) gena subequal to compound eye in width, slightly excavated below, this area fringed with dense, yellowish, rather short hairs, 5) vertex and gena quite uniformly, finely and densely punctate, lower portions of face in large part very finely and closely punctate beneath dense pubescence that completely hides surface, 6) pubescence of face and vertex yellowish, dense below level of antennae, rather elongate on vertex medially, becoming shorter, more inconspicuous laterally, very sparse and short on gena, becoming somewhat paler and more dense along lower margin, 7) F1 about as long as broad, almost twice as long as pedicel, and shorter than remaining flagellomeres, which are longer than broad (2:1.5), apical flagellomere very broadly dilated.

Mesosoma. 1) pubescence rather dense, not very elongate, pale yellowish on pleura and propodeum, somewhat deeper yellow and rather short and erect but not hiding dorsal surface, 2) mesoscutum and scutellum dull, with very fine, densely crowded punctures, those on pleura minute and densely crowded, propodeum somewhat more shining, with close but rather vague and indistinct punctures, triangle dull and impunctate, 3) front coxal spine robust, rather acutely pointed apically, broad at base, with a large transverse patch of suberect, reddish-brown bristles at base, coxa otherwise largely bare; front tarsus pale yellow, rather broadly dilated, about equal to tibia, but anterior margin only very obscurely or shallowly excavated, posterior fringe dense, about equal in length to breadth of each tarsomere, whitish toward apical tarsomere, more yellowish-brown at base, outer face of front tibia black, with apical margin yellowish, other two faces more reddish-brown, and posterior face of front femur black, with lower margin carinate and yellowish, other faces largely yellowish-brown, densely fringed posteriorly with yellowish hairs that are elongate toward base; mid tibial spurs well developed; middle basitarsus slightly narrower, considerably shorter than tibia, with a much elongated, yellowish, posterior fringe; hind femur somewhat swollen, hind basitarsus about half the length of its tibia, 4) tegula very minutely and closely punctate, anterior part quite densely pubescent, 5) wings subhyaline, very faintly clouded apically, veins black.

Metasoma. 1) T2 and T3 quite deeply depressed at base, T4 and T5 more shallowly so, basal margin of depressions distinct, carinate, apical margins of terga uniformly, rather deeply depressed, very deeply so on T4 and T5, the discs overhanging the depressed rims, with dense, entire, yellowish, apical fasciae on T2-T5; T1 with copious, elongate, yellowish pubescence, apical fringe rather obscure, discal pubescence of T2-T5 erect, conspicuous, entirely pale, but not obscuring the fasciae, T5 more or less bare apically, punctures very fine and close throughout, minute on the more basal terga, becoming somewhat more irregular on T5 apically, T6 rather densely tomentose, very closely and finely punctate beneath the pubescence, with a slight median ridge, and slightly depressed on each side, the carina slightly down curved and truncate, with no median emargination, median apical teeth broadly carinate, much nearer the very small lateral angles than to each other; T7 angulate medially, 2) S1-S4 very finely, uniformly and closely punctate, discal surfaces sparsely pubescent, apical margins of S1-S3 depressed, yellowish-hyaline, quite densely fasciate, the fasciae much broader laterally, S4 not conspicuously fringed but with a quite distinct, median, carinate and acute tubercle.

Genitalia. Plate 2, Figure G33.

Discussion. This is our largest indigenous Megachile, and one of the most uncommon in Canada. Megachile fortis is considered to be a specialist of Helianthus and nests in the ground (Neff and Simpson 1991). Fischer (1956) gave an account of the morphology and reproductive mechanisms of the male.

Distribution. Southern MB-BC


Names
Scientific source:

Supported by

Hosts · map
FamilyScientific name @ source (records)
Asteraceae  Helianthus annuus @ UCRC_ENT (1)

Helianthus pauciflorus @ UCRC_ENT (1)

Helianthus sp @ AMNH_BEE (1)

Helianthus @ AMNH_BEE (4)
Fabaceae  Lotus wrightii @ BBSL__KWC (1)

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Updated: 2019-10-20 09:24:54 gmt
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