Pristaulacus rufitarsis
(Cresson, 1864)
Pristaulacus rufitarsis is a parasitic wasp in the Aulacidae, found in North America. The is a of wood-boring larvae, specifically targeting species such as the Hemlock borer (Phaenops fulvoguttata) and the poplar borer (Saperda calcarata). Females locate larvae in wood by probing crevices with their , then use their curved ovipositor to deposit . The species has been documented in Colorado and Alberta, Canada.
Pronunciation
How to pronounce Pristaulacus rufitarsis: /prɪsˈtaʊləkəs ˌrʌfɪˈtɑrsɪs/
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Identification
Aulacid wasps can be distinguished from superficially similar ichneumon wasps by three key characters: the attaches high on the (not low), there is a short 'neck' behind the , and the ovipositor is downcurved at the tip rather than straight. In Pristaulacus rufitarsis specifically, the name 'rufitarsis' (red legs) suggests reddish that may aid in identification. The Pristaulacus is generally larger than the related genus Aulacus.
Habitat
Found in association with freshly cut or dead wood, particularly logs and slash piles of coniferous trees such as Ponderosa Pine. The is attracted to aromatic compounds emitted by cut, living wood that signal the presence of potential .
Distribution
North America; documented from Colorado, USA and Alberta, Canada. GBIF records confirm presence in Canada (Alberta) and the United States.
Host Associations
- Phaenops fulvoguttata - Hemlock borer, a wood-boring in Buprestidae
- Saperda calcarata - Poplar borer, a wood-boring in Cerambycidae
Behavior
Females walk haltingly across log surfaces, bobbing their slightly and slowly rowing their wings. They probe cracks and crevices by inserting their deeply, apparently using this to locate larvae. Once a host is located, the female uses grooves on the inner surface of her hind to guide and stabilize her ovipositor during insertion into wood. Males have been observed to be smaller than females; mating may occur away from host .
Ecological Role
Primary of wood-boring beetles, contributing to of these insects in forest . By parasitizing larvae in dead and dying trees, the plays a role in nutrient cycling and forest health.
Similar Taxa
- Pristaulacus fasciatusSimilar size, distribution, and preferences; both occur in North American forests and parasitize wood-boring beetles. P. fasciatus has been documented from eastern Texas and Nebraska eastward, with females averaging around 16 mm body length.
- Ichneumonidae (family)Superficially similar appearance and , but distinguished by abdominal attachment point (low on in ichneumons, high in aulacids), presence of a short 'neck' in aulacids, and straight ovipositor in ichneumons versus downcurved in aulacids.
- Aulacus (genus)Related in same , but are typically smaller than Pristaulacus and may differ in preferences.
More Details
Taxonomic History
described by Cresson in 1864. The Pristaulacus is one of two genera in Aulacidae, with Aulacus being the other.
Collection Notes
Specimens have been collected at logging mill operations and slash piles of freshly-cut pine. One photographed specimen was obtained in Black Forest, Colorado at a site with abundant wood-boring beetles including Chrysobothris dentipes, Phaenops gentilis, and various Cerambycidae.