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McMillan's Biting Midge (Austroconops mcmillani)

McMillan's biting midge is a Western Australian biting midge known from the Swan Coastal Plain, with very limited recorded occurrence information. Its immature stages are associated with very wet soil or detritus, so works affecting these substrates warrant precaution. It is listed as Priority 2 on the WA DBCA list.

Conservation status

Western Australia, WA Threatened and Priority Fauna List: Priority 2.

Seasonal planning

Activity and breeding months are not documented for this species.

Breeding period: Not recorded.

Survey season: Not recorded; seek specialist advice on timing.

The seasonal row is a general planning prompt and does not indicate known seasonal activity.

  • Precautionary survey and works planning: Planning window only. No species-specific months are known, so assess potential impacts whenever works may affect very wet soil or detritus.

Identification: Appearance and size

Life-stage information is documented, but field identification characters and measurements are not.

No diagnostic appearance, colour or size data are recorded for Austroconops mcmillani. Eggs, all four larval instars and the pupa have been described.

Identification: Similar species

Austroconops annettae is another extant species of the genus. No field characters to distinguish it from A. mcmillani are documented.

Identification: Field signs

No species-specific field signs are documented. Larvae in very wet soil or detritus may be relevant to an assessment, but their presence should be confirmed by a suitably qualified specialist.

Distribution: Known range

The species is recorded in Western Australia, with very few occurrence data.

Atlas of Living Australia records show one Western Australian record in one distinct 0.1-degree location, with a coordinate range of latitude -31.5 and longitude 115.7. Records outside WA are excluded as likely errors.

Distribution: WA regions and locality

The DBCA list flags the Swan region. The DBCA common name refers to the Swan Coastal Plain, but no more precise named collection locality is recorded.

Distribution: Listing

The species is Priority 2 on the DBCA Threatened and Priority Fauna List dated 1 July 2025. This is a DBCA priority category, not a listing under the Biodiversity Conservation Act 2016. No national listing is recorded.

Habitat: Recorded habitat information

The clearest habitat information concerns the immature stages and their association with very wet substrate.

The larvae of Austroconops are described as aquatic and feeding in very wet soil or detritus. No specific vegetation type, landform or site condition is identified for A. mcmillani.

Habitat: Site assessment

Where works are proposed in the Swan region, note patches of very wet soil and detritus for specialist assessment. A particular vegetation community or wetland type has not been established for this species.

Foraging habitat: Larval feeding

Some feeding information is documented, but the precise places and conditions in which feeding occurs are unknown.

Larvae feed on microscopic organisms in very wet soil or detritus. Specific prey and field signs of feeding sites have not been documented.

Foraging habitat: Adult feeding

Adult females are reported to bite humans and kangaroos. Other adult food sources and the habitat used for adult feeding are not documented.

Breeding habitat: Known life stages

Early life stages have been described, but breeding sites and timing are unknown.

Eggs and all four larval instars of A. mcmillani have been described, as has its pupa. Larvae feed in very wet soil or detritus.

Breeding habitat: Unknown breeding details

Egg-laying sites, development time and breeding months have not been documented. Do not infer a breeding season from the reported life stages.

Sheltering habitat: Available information

No species-specific shelter, resting site or refuge is recorded.

Larvae are associated with very wet soil or detritus, but this substrate is not documented as a shelter. Adult resting places are not recorded.

Sheltering habitat: Precaution

When assessing a site, retain and document wet soil and detritus patches until their fauna value has been checked. Do not assume that dry-looking edges or adjacent ground are unoccupied refuges.

Threats: Known information

No specific threats to this species are documented.

A. mcmillani is listed as Priority 2 because it is poorly known and known from few locations, with some locations on conservation lands. No species-specific threatening process is documented.

Threats: Works-related considerations

Avoid unnecessary disturbance to very wet soil and detritus where the species may occur. This precaution is based on the documented larval association; no particular works impact has been demonstrated for the species.

Survey methodology: 1. Desktop assessment

No validated survey method or information on the species' detectability is documented.

Check current DBCA information and records for the project area, including the Swan region and the limited Atlas record. Do not assume the species is absent because no records are mapped.

Survey methodology: 2. Habitat inspection

Map and photograph very wet soil and detritus within the proposed disturbance area. Record the extent and condition of these patches and any changes to water levels or drainage that may be relevant to the site assessment.

Survey methodology: 3. Specialist survey

Obtain advice from a suitably qualified invertebrate specialist on whether targeted sampling is warranted and on appropriate methods, timing, permits and specimen handling. No season or method that ensures detection has been established.

Vegetation associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific vegetation association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Ecosystem associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific ecosystem association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Soil and substrate associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific soil association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Water and wetland associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific water association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Fauna records and mapped habitat: Not yet analysed

Record locations can be overlaid with mapping, but record frequency alone does not measure habitat preference. No species is excluded from desktop assessments by this analysis.

No quality-controlled record-to-map analysis has been completed for this species. The existing generalised distribution dots and indicative range polygons have not been treated as precise occurrence coordinates.

A defensible run needs dated, independently attributable records, coordinate uncertainty, duplicate and captive-record checks, layer versions and regional scope. Preference and absence require additional survey-effort and detection evidence.

Habitat limitations and contrary evidence: No supported exclusion recorded

Not recorded is not the same as cannot occur. Low suitability, resident habitat, breeding habitat and occasional movement are different conclusions.

This library has not established a vegetation, ecosystem or soil-type exclusion for this species. This does not mean all habitat is suitable; the evidence needed to justify an exclusion has not been assembled.

Habitat limitations and contrary evidence: Before using a negative association

  • Confirm the taxon, geographic region, life stage and habitat function covered by the evidence.
  • Check survey methods, season, repeated effort and detectability before interpreting non-detection.
  • Investigate credible contradictory records and microhabitats absent from broad mapping.
  • Do not convert a missing map class, low record count or failed data request into species absence.

Before habitat disturbance: 1. Confirm constraints

Plan works with the species' uncertain occurrence and its documented association with very wet soil or detritus in mind.

Review the project footprint against DBCA information and available occurrence records. Seek specialist advice if very wet soil or detritus may be affected.

Before habitat disturbance: 2. Mark and brief

Mark areas to be retained or assessed before clearing begins. Brief spotter catchers and crews on the limited species information, the substrate of concern, stop-work procedures and the need to report potential specimens.

Before habitat disturbance: 3. Prepare controls

Set out practical controls to avoid unnecessary disturbance and changes to drainage in retained wet patches. Agree in advance who will make decisions if a potential specimen is found.

During habitat disturbance: 1. Work to marked limits

Use a cautious, staged approach where works could affect wet soil or detritus.

Keep clearing and ground disturbance within approved limits. Avoid unnecessary tracking, soil stripping or drainage changes in patches identified for retention or assessment.

During habitat disturbance: 2. Respond to potential finds

If a possible Austroconops mcmillani or relevant immature stage is encountered, pause work in the immediate area, protect the find from further disturbance and contact the project ecologist or nominated invertebrate specialist. Do not handle or relocate specimens unless directed and authorised.

During habitat disturbance: 3. Record changes

Document the location, substrate and circumstances of any potential find, and record any unexpected disturbance to wet soil or detritus. Resume affected work only after the agreed environmental response is in place.

After habitat disturbance: 1. Inspect retained areas

Check that site controls remain effective and pass relevant observations to the project ecologist.

Check retained patches and their boundaries after disturbance for accidental clearing, soil damage or drainage changes. Address any departure from the approved controls promptly.

After habitat disturbance: 2. Close out records

Keep records of survey effort, habitat observations, potential finds and the actions taken. Submit confirmed records through the appropriate channels and update project documentation.

Rehabilitation actions: 1. Protect retained substrate

Rehabilitation should not assume that generic planting or earthworks will recreate suitable habitat for this poorly known species.

Prioritise retaining undisturbed wet soil and detritus where practicable. Avoid unapproved changes to local drainage or soil levels in retained areas.

Rehabilitation actions: 2. Plan site-specific recovery

If rehabilitation affects areas associated with very wet soil or detritus, seek ecologist advice on site-specific objectives and monitoring. No species-specific rehabilitation method or success measure is established.

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