Auplopus caerulescens
(Dahlbom, 1843)
Blue Mud-dauber Spider Wasp
Auplopus caerulescens is a small spider-hunting in the Pompilidae, tribe Auplopini. Females construct distinctive barrel-shaped mud , typically 15 mm long and 7-10 mm wide, often placed inside pre-existing cavities such as hollows in wood, rock crevices, or abandoned nests of other wasps. The is known for its bright metallic blue-green coloration, with females bearing a diagnostic pygidial plate used to manipulate mud during nest construction. It is widely distributed across North America.
Pronunciation
How to pronounce Auplopus caerulescens: //ˈɔː.plə.pəs saɪˌruːˈlɛs.ɛnz//
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Identification
Small metallic blue-green pompilid with diagnostic pygidial plate on female . Distinguished from other Auplopus by subtle morphological features; males require genitalia examination for definitive identification. Nests are characteristic barrel-shaped mud , often found in clusters within cavities.
Appearance
Small averaging approximately 10 mm in length. Females exhibit bright metallic blue-green coloration. A key diagnostic feature is the oval pygidial plate located dorsally on the near the tip, which functions as a masonry trowel for nest construction. Males are distinguished by genitalia differences and lack the prominent pygidial plate. The body is compact with typical pompilid proportions.
Habitat
Utilizes pre-existing cavities in wood, rock crevices, under bark on standing trees, and sheltered . Frequently colonizes abandoned nests of other including Sceliphron caementarium, Trypoxylon politum, and Polistes paper wasps. Also documented nesting in concrete cellar foundations.
Distribution
Widespread across North America. Documented in upstate New York and across the continent. The nominate Auplopus caerulescens caerulescens occurs in the Palearctic region as well.
Seasonality
Active from May through October, with peak abundance July through September.
Diet
Spiders (Araneae). Documented prey includes multiple : Thomisidae (crab spiders), Salticidae (jumping spiders), Clubionidae (sac spiders), Corinnidae (ground sac spiders), Anyphaenidae (ghost spiders), Miturgidae (longlegged sac spiders), Gnaphosidae (ground spiders), and Pisauridae (nursery web spiders). feed on honeydew.
Life Cycle
Female constructs mud , provisions it with paralyzed spiders (often amputating legs to facilitate transport and feeding), lays single attached to spider prey, and seals cell with mud cap. Larva feeds on paralyzed spiders, to pupa within cocoon. Emerging regurgitates liquid to soften mud cap before chewing exit hole. Development period varies; some individuals may overwinter as pupae.
Behavior
Solitary nesting with females working alone. Demonstrates selectivity in prey capture at level; some individuals show consistent prey preferences. Prey transport involves dragging amputated spiders over ground. Mud manipulation accomplished by curling beneath body to apply pygidial plate to mud pellets. frequently found around colonies feeding on honeydew.
Ecological Role
of spiders, particularly non-web-building . Functions as provisioning , with larvae consuming paralyzed prey. Potential for nest (specific parasitoid associations not well documented).
Human Relevance
Non-aggressive; solitary rarely sting even when disturbed. Nests occasionally considered unsightly when attached to human structures, but pose no threat. Occasionally enters buildings through existing cavities.
Similar Taxa
- Auplopus carbonariusIntroduced Palearctic ; external similar, requires genitalia examination for definitive identification
- Eumenes spp. (potter wasps)Construct mud nests but produce distinctive urn-shaped pots with fluted necks, not barrel-shaped ; Vespidae
- Trypoxylon politumConstructs linear mud tube nests with multiple , not discrete barrel-shaped cells; male-female cooperative nesting differs from solitary Auplopus
- Sceliphron caementariumBuilds larger multi-cellular mud nests covered in additional mud layers; black and yellow coloration, not metallic blue-green
- Osmia spp. (mason bees)Some construct similar mud ; bees not , with different prey provisioning (pollen/nectar vs. spiders)