Megachile (Argyropile)

Taxonomy

Family: Megachilidae
Subfamily: Megachilinae
Tribe: Megachilini
Genus: Megachile Latreille, 1802
Subgenus: Argyropile Mitchell, 1934
Common name: none

Overview

Megachile (Argyropile) often have a black integument with white, tan, or reddish hairs throughout their body, usually forming apical bands of hair on their terga (Michener 2007). They range in body length from 9–16 mm (Michener 2007; Gonzalez 2008).

Diagnostic characteristics

(modified from Mitchell 1937a; Mitchell 1943; Michener 2007; Gonzalez 2008)

  • Female mandible is four-toothed with the inner tooth sometimes incised, which can give it the appearance of five teeth. The cutting edge between the second and third teeth is shorter and narrower than the edge between the third and fourth teeth, which is evenly concave.
  • Female S6 apical rim is angled upwards and is either thick or rolled.
  • Female S6 is mostly bare rim behind a fringe of preapical hairs.
  • Male antenna with apical segment unmodified and not expanded.
  • Male front tarsi are simple, slender, and dark-colored or fuscous.
  • Male front coxal spine is small and slender and lacks an anterior patch of red hairs at the base.
  • Male gonoforceps are narrowed above the base, slender, apically compressed, and shorter than the penis valve.
  • Male mandible with small inferior process.
  • Male S6 apical margin has acute median teeth and conspicuous lateral teeth.

May be confused with

Female Megachile (Argyropile) may be confused with bees within the subgenera Megachile (Pseudocentron) and Megachile (Acentron) because the female S6 mostly lacks hair and the apical edge is bent upwards (Michener 2007; Gonzalez 2008). However, Megachile (Argyropile) has a thick apical rim, while the other two subgenera have thinner and translucent rims (Gonzalez 2008). Megachile (Argyropile) also has a fully developed middle tibial spur, whereas Megachile (Pseudocentron) lack the middle tibial spurs and have an immovable prong or tooth instead (Michener 2007). All three subgenera differ in their mandibular structure.

Host associations

Megachile (Argyropile) are generalists and have been observed visiting a variety of species within Asclepiadaceae, Asteraceae, Bignoniaceae, Brassicaceae, Capparaceae, Fabaceae, Hydrophyllaceae, Hypericaceae, Lamiaceae, Malphighiaceae, Malvaceae, Onagraceae, Polemoniaceae, Polygonaceae, Rhamnaceae, Rubiaceae, Sapindaceae, Tamariaceae, Verbenaceae, and Zygophyllaceae (Butler 1965; Gonzalez and Griswold 2007; Gonzalez 2008). However, Megachile (Argyropile) shows a preference for Asteraceae (Mitchell 1937a; Gonzalez 2008).

Nesting behavior

Megachile (Argyropile) have been observed nesting in trap nests and burrowing shallow nests in the ground, particularly in sandy soil (Fischer 1951; Butler 1965; Medler and Lussenhop 1968; Neff and Simpson 1991). The nests are lined with leaves, some of which were identified as Spiraea (Rosaceae) or Trifolium (Fabaceae) (Fischer 1951).

Diversity

Megachile (Argyropile) is a subgenus of seven species, five of which are found in the U.S. (Gonzalez 2008).

Known invasives

There are no known invasives. 

Distribution

Megachile (Argyropile) occur throughout North and Central America. They are distributed from southwest Canada to Costa Rica (Mitchell 1937a; Gonzalez 2008).

Distribution
​Distribution map generated by Discover Life -- click on map for details, credits, and terms of use.

<p><em>Megachile townsendiana </em>female face, photo: Jeni Sidwell</p>
Megachile townsendiana female face, photo: Jeni Sidwell
<p><em>Megachile townsendiana </em>female lateral habitus, photo: Jeni Sidwell</p>
Megachile townsendiana female lateral habitus, photo: Jeni Sidwell
<p><em>Megachile townsendiana </em>female abdomen, photo: Jeni Sidwell</p>
Megachile townsendiana female abdomen, photo: Jeni Sidwell
<p><em>Megachile flavihirsuta</em> male face, photo: Jeni Sidwell</p>
Megachile flavihirsuta male face, photo: Jeni Sidwell
<p><em>Megachile flavihirsuta</em> male lateral habitus, photo: Jeni Sidwell</p>
Megachile flavihirsuta male lateral habitus, photo: Jeni Sidwell
<p><em>Megachile flavihirsuta</em> male abdomen, photo: Jeni Sidwell</p>
Megachile flavihirsuta male abdomen, photo: Jeni Sidwell
<p><em>Megachile flavihirsuta</em> female hypostomal area, photo: Joshua Hengel</p>
Megachile flavihirsuta female hypostomal area, photo: Joshua Hengel
<p><em>Megachile sabinensis</em> male apical terga, photo: Colleen Meidt</p>
Megachile sabinensis male apical terga, photo: Colleen Meidt