Lithurgus

Taxonomy

Family: Megachilidae
Subfamily: Lithurginae
Tribe: Lithurgini
Genus: Lithurgus Berthold, 1827
Subgenera: none
Common name: none

Overview

Lithurgus has a slightly elongated and flattened abdomen (Michener 2007). They are black with pale yellow or white bands of hair on their terga. They range in body length from 8–19 mm (Michener 2007).

Diversity

Lithurgus contains 33 species (Gonzalez et al. 2013); 2 species are known to occur in the U.S. (Wilson and Carril 2016).

Diagnostic characteristics

(modified from Michener 2007 unless otherwise stated)

  • Arolia absent in both sexes (Fig 5).
  • First flagellar segment about twice as long as broad and more than twice as long as the second, which is broader than long.
  • Hind tibia with course tubercles that do not end in bristles (Fig 4).
  • Labrum about as long as clypeus (Gonzalez et al. 2013).
  • Male pygidial plate present.
  • Female with facial prominence involving the upper part of clypeus as well as part of the supraclypeal area.
  • Female with median apical process or spine on T6.
  • Female tarsal claws are simple (Fig 5).

May be confused with

Lithurgus looks similar to some Megachile and Austrothurgus but can be distinguished by the characters listed above (Michener 2007).

Known invasives

L. chrysurus is adventive to the U.S. It was accidentally introduced in the early to mid-1970s from the western Mediterranean (Roberts 1978). It is currently known to be established in a limited area of Pennsylvania and New Jersey, although at apparently small numbers (Russo 2016).

L. scabrosus was introduced to Hawaii from the South Pacific sometime before 1907; it probably arrived with Europeans (Snelling 2003; Russo 2016). It is known from Kauai and Oahu, and frequently visits Hibiscus flowers (Snelling 2003).

Host associations

Lithurgus tends to be specialized on either Malvaceae or Asteraceae (Wilson and Carril 2016). In the U.S., L. chrysurus is specialized on Centaurea (Wilson and Carril 2016), and it seems to prefer the noxious invasive spotted knapweed (C. stoebe micranthos), which is also from the Mediterranean (Roberts 1978). The disparity between the widespread occurrence of the host weed, which has already spread throughout the western and northern U.S., and the currently limited range of L. chrysurus is interesting.

Nesting behavior

Lithurgus is a solitary, although often very gregarious, genus of wood-boring bees. They burrow into and nest inside dead rotting wood as well as firm nondegraded hardwood, firewood, man-made wood structures, or wood-based materials following the wood grain (Roberts 1978; Rust et al. 2004; Rozen and Wyman 2013; Rozen and Wyman 2014). One elongated cell may contain multiple provisions with brood contained one after another in a linear series. Wood materials are sometimes used to partition the nest into multiple separate cells (Roberts 1978; Rust et al. 2004). The habit of burrowing into wooden structures like crates, fiber composite building materials, beams, and timbers increases both the likelihood of being transported by people as well as their potential economic destructiveness (Rust et al. 2004; Rozen and Wyman 2014).

Distribution

Lithurgus occurs natively in various places throughout the Old World. In the U.S., it is represented by two introduced species: L. chrysurus and L. scabrosus (Michener 2007). One species, Lithurgus huberi, can be found in South America.

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

<p><em>Lithurgus chysurus </em>male face, photo: C. Ritner</p>
Lithurgus chysurus male face, photo: C. Ritner
<p><em>Lithurgus chyrusus</em> male lateral habitus, photo: C. Ritner</p>
Lithurgus chyrusus male lateral habitus, photo: C. Ritner
<p><em>Lithurgus chrysurus</em> male abdomen, photo: T. Brady</p>
Lithurgus chrysurus male abdomen, photo: T. Brady
<p><em>Lithurgus chrysurus</em> female hind tibia tuberculate, photo: C. Ritner</p>
Lithurgus chrysurus female hind tibia tuberculate, photo: C. Ritner
<p><em>Lithurgus chrysurus</em> female simple tarsal claw and arolia absent, photo: C. Ritner</p>
Lithurgus chrysurus female simple tarsal claw and arolia absent, photo: C. Ritner
<p><em>Lithurgus apicalis </em>nest, photo: C. Ritner</p>
Lithurgus apicalis nest, photo: C. Ritner