Hedriodiscus truquii

Hedriodiscus truquii belongs to the tribe Stratiomyini, which includes the similar genus Psellidotus. These two genera are readily separable in the Nearctic region but distinctions become less clear in the Neotropics. Adults likely exhibit the horizontally banded eye patterns characteristic of many Stratiomyinae, possibly indicating polarization vision capabilities. Specific diagnostic features for distinguishing H. truquii from congeners are not documented in available sources.

Thermal spring communities with aquatic conditions. Documented from two springs in Washington State with mean temperatures of 35°C and 47°C respectively. Larvae are aquatic, inhabiting the algal mats and submerged vegetation of these heated, mineral-rich waters. The species has been observed in springs with differing floral and faunal compositions, suggesting adaptability to varying thermal and biological conditions within the thermal spring ecosystem.

United States (Washington State—documented from Mount Rainier National Park; also recorded from other states), Mexico, and El Salvador. Distribution records suggest a range spanning temperate and subtropical regions of North and Central America.

Larvae are herbivores, feeding on algae. In the studied thermal springs, only 0.5–1.0% of algal primary production was channeled to Hedriodiscus populations, indicating that while abundant, the species processes a relatively small fraction of available algal biomass. Adult diet is not documented.

Four larval instars documented. Larval growth shows seasonal variation in lipid composition, which correlates with observed caloric variation. Energy budgets have been calculated for three of the four instars based on growth, respiration, and food ingestion rates. Pupation occurs in the soil or substrate of the aquatic habitat. Heavy mortality occurs at the adult emergence stage due to predation.

Larvae exhibit diel behavior patterns that vary between populations, affecting energy allocation and metabolic efficiency. Newly emerged adults are vulnerable to predation, particularly by spiders. Larvae are subject to export from the system, representing a significant source of population mortality and energy loss from the community.

Dominant herbivore and principal macroinvertebrate consumer in thermal spring communities studied. Serves as a critical conduit for energy transfer from primary producers (algae) to higher trophic levels, particularly predators. Population energy budgets indicate substantial role in ecosystem energetics despite processing a small percentage of total algal production. Represents a significant prey resource for spiders and other predators. Larval export contributes to energy loss from the spring system.

• PsellidotusClosely related genus within tribe Stratiomyini; morphologically similar and easily confused, especially in the Neotropics where generic boundaries become less distinct. Both genera share aquatic larval habits and adult eye patterning.

• soldier fly
• thermal spring
• aquatic insect
• herbivore
• ecological energetics
• algal feeder
• predation vulnerability

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Diptera | Beetles In The Bush | Page 5
• Ecological Energetics and Natural History of Hedriodiscus truquii (Diptera) in Two Thermal Spring Communities