Auplopus mollis
Townes, 1957
Auplopus mollis is a small in the , tribe Auplopini. Females construct distinctive free-standing mud , typically barrel-shaped and approximately 15 mm long by 7–10 mm wide, often stacked end-to-end in rows of two to five. The hunts non-web-building , amputates their legs to facilitate transport, and provisions each mud cell with multiple paralyzed spiders before laying a single . feed on rather than visiting flowers.
Pronunciation
How to pronounce Auplopus mollis: /ˈɔːpləˌpʊs ˈmɒlɪs/
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Identification
Distinguished from other mud-nesting by the small, barrel-shaped mud constructed in pre-existing cavities rather than as free-standing exposed structures. Cells are smaller and more delicate than those of Sceliphron caementarium (black and mud dauber) and lack the fluted urn shape of Eumenes . Differs from Trypoxylon politum (pipe organ mud dauber) in cell arrangement: Auplopus cells are stacked barrels rather than linear partitioned tubes. May be confused with Osmia or Eumeninae that construct similar mud nests; examination of the wasp or nest contents ( versus pollen/nectar provisions) confirms identity.
Images
Appearance
Small averaging approximately 10 mm in length. Females possess a characteristic oval pygidial plate on the surface of the near the tip, used as a masonry trowel to manipulate mud pellets during nest construction. Several Auplopus exhibit bright metallic -green coloration; females of these species are externally indistinguishable without examination of male for definitive identification.
Habitat
Constructs nests in sheltered pre-existing cavities including holes in wood, crevices in rock walls, spaces under bark on standing trees, and abandoned nests of other . Nests are not built in exposed locations but require protection from direct weather. often found in proximity to colonies on honeyvine , sunflower, and other plants.
Distribution
North America; occurs across the continent with records from Arizona and other western states. The Auplopus is widespread continentally, though -level distributions require further revision.
Seasonality
Active from May through October, with peak abundance from July through September.
Diet
feed on , the sugary liquid waste secreted by . are provisioned with paralyzed from including Thomisidae (crab spiders), Salticidae (), Clubionidae (), Corinnidae (ground sac spiders), Anyphaenidae (ghost spiders), Miturgidae (longlegged sac spiders), Gnaphosidae (ground spiders), and Pisauridae (nursery web spiders). Both adult and spiders may be taken as .
Life Cycle
Female constructs mud , provisions it with multiple paralyzed (often with legs amputated), lays single on final spider victim, and seals cell with mud cap. hatches and consumes fresh paralyzed . Upon maturity, larva molts into within ; in at least some , emerging regurgitates liquid to soften mud cap before chewing exit hole. Development may complete in several weeks or pupa may overwinter for extended period.
Behavior
Solitary nesting ; each female constructs and provisions her own nest without cooperation. Females exhibit specialized mud-manipulation behavior, curling beneath body to apply pygidial plate to mud pellets. transport involves amputating legs, which reduces prey size and allows the to feed on spider . demonstrate opportunistic hunting of non-web-building spiders and frequent colonies for feeding.
Ecological Role
of , potentially influencing local spider . Contributor to through subduing and larval consumption. serve as consumers of , though ecological significance of this feeding mode is unquantified. Nests in abandoned may contribute to structure of cavity-nesting .
Human Relevance
Non-aggressive; solitary do not defend nests and are rare unless wasp is directly handled. Nests may be encountered in human structures including abandoned bolt holes, rock walls, and eaves. No significant pest status; occasional nuisance if nests discovered in high-visibility locations. Potential educational and scientific value for studying - relationships through nest rearing.
Similar Taxa
- Sceliphron caementariumAlso constructs mud nests, but builds larger, clod-like multi-cellular structures covered in additional mud layers rather than discrete small barrels.
- Trypoxylon politumBuilds linear partitioned mud tubes rather than stacked barrel ; often constructs exposed nests on flat surfaces.
- Eumenes spp. construct exposed urn-shaped mud pots with fluted necks, not barrel in cavities; provision nests with rather than .
- Osmia spp. construct similar mud but provision with pollen and nectar rather than ; are not .
More Details
Taxonomic Status
The Auplopus is in need of revision; ten are recognized in North America but species boundaries, particularly among metallic -green forms with externally identical females, remain poorly resolved.
Introduced Species
A. carbonarius, from western Europe, has been documented in New York and Michigan and likely has a broader U.S. distribution than currently recorded.
Nest Associates
Auplopus mollis and frequently construct nests inside abandoned nests of Sceliphron caementarium, Trypoxylon politum, and Polistes .