Sphecophaga vesparum

Distinguished from other ichneumonids by its specialized association with vespid wasp nests and the presence of two female morphs (winged and brachypterous). The three cocoon types (white, weak yellow, thick yellow) are diagnostic. Subspecies identification requires color character analysis; morphological characters alone do not reliably separate S. v. vesparum from S. v. burra.

Adults occur in two distinct female morphs. Large winged females are fully alate. Small brachypterous females have reduced wings. Cocoons show three color and texture variants: soft white cocoons, weak-walled yellow cocoons, and rigid thick yellow cocoons used for overwintering. Subspecies S. v. vesparum and S. v. burra are morphologically indistinguishable but can be separated by color characters with >98% accuracy for females and 100% for males.

Exclusively associated with nests of social vespid wasps, particularly Vespula species. Found within the capped brood cells of host colonies where immature wasps are present.

Native to Europe (Belgium, United Kingdom, Denmark, Norway, Flemish Region). Introduced to New Zealand (established at Pelorus Bridge, Marlborough and Ashley Forest, Canterbury) and Australia (released in Victoria).

Winged adults emerge from overwintering yellow cocoons after 1–4 years of dormancy and may live up to 3 weeks. Brachypterous females emerge from white cocoons within approximately 13 days. Multiple generations can occur within a single year in active wasp nests.

Ectoparasitic larvae feed on immature wasps, specifically newly pupated forms within capped cells of host nests.

• Vespula vulgaris - primary hostCommon wasp; main host in introduced range
• Vespula germanica - primary hostGerman wasp; main host in introduced range

Ectoparasitic on wasp pupae within capped cells. Females oviposit preferentially into cells where host pupation has most recently occurred. Three egg/cocoon types determine adult phenotype: white cocoons produce brachypterous females in ~13 days; weak yellow cocoons produce winged females (and possibly males) in ~15 days; thick yellow cocoons are overwintering, producing winged adults after 1–4 years. Many generations may originate from one invasive winged female in one year.

Females preferentially oviposit on host immatures that have recently spun pupal caps. Winged adults may live up to 3 weeks. The species exhibits partial chemical mimicry of host cuticular hydrocarbons, particularly linear alkanes, likely through passive recycling of prey hydrocarbons to avoid host detection. Dispersal of at least 2.37 km per year has been documented in New Zealand.

Ectoparasitoid that regulates populations of social vespid wasps. Functions as a biological control agent for invasive Vespula species in New Zealand and Australia. Has established self-sustaining populations at limited sites in New Zealand with parasitism rates averaging 8.5% of nests annually at Pelorus Bridge.

Introduced as a biological control agent for invasive German and common wasps in New Zealand (releases 1985–1987, 1987–ongoing) and Australia (approved 1989, released in Victoria). Establishment has been limited and localized; no significant reduction in wasp nest density has been demonstrated despite increased parasitism rates over time. Further releases of S. v. vesparum not recommended; S. v. burra considered for re-release.

• Sphecophaga vesparum burraNorth American subspecies morphologically indistinguishable but separable by color characters; failed to establish in New Zealand field releases
• Other IchneumonidaeLack specialized vespid nest association, two female morphs, and three cocoon types

• ectoparasitoid
• biological control
• parthenogenesis
• polyphenism
• chemical mimicry
• invasive species management

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Invasion success of the wasp parasitoid Sphecophaga vesparum vesparum (Curtis) in New Zealand
• Hydrocarbon Signatures of the Ectoparasitoid Sphecophaga vesparum Shows Wasp Host Dependency
• Factors influencing reproductive strategies of the vespid parasitoid Sphecophaga vesparum vesparum (Hymenoptera: Ichneumonidae)
• Release and recovery of the introduced wasp parasitoid, Sphecophaga vesparum vesparum (Curtis) (Hymenoptera: Ichneumonidae) in New Zealand
• Morphological and colour differences between subspecies of Sphecophaga vesparum (Hymenoptera: Ichneumonidae)
• Establishment of the wasp parasitoid, Sphecophaga vesparum (Hymenoptera: Ichneumonidae), in New Zealand
• Mortality and Emergence Pattern of Overwintering Cocoons of the Wasp ParasitoidSphecophaga vesparum vesparum(Hymenoptera: Ichneumonidae) in New Zealand
• Life cycle of Sphecophaga vesparum (Curtis) (Hymenoptera: Ichneumonidae), a parasitoid of some vespid wasps
• Rearing and distribution of the introduced wasp parasitoid <i>Sphecophaga vesparum</i> throughout New Zealand
• Potential enemies of the introduced wasp parasitoid Sphecophaga vesparum (Hymenoptera: Ichneumonidae) in New Zealand
• Can the wasp parasitoid Sphecophaga vesparum significantly reduce the density of Vespula wasps?
• Attempted biological control of social wasps, Vespula spp., (Hymenoptera: Vespidae) with Sphecophaga vesparum (Curtis) (Hymenoptera : Ichneumonidae) in New Zealand
• No evidence for establishment of the wasp parasitoid, Sphecophaga vesparum burra (Cresson) (Hymenoptera: Ichneumonidae) at two sites in New Zealand
• Host specificity of the parasitoid, Sphecophaga vesparum (Curtis) (Hymenoptera: Ichneumonidae), a potential biological control agent of the social wasps, Vespula germanica (Fabricius) and V. vulgaris (Linnaeus) (Hymenoptera: Vespidae) in Australia