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Solitary midges (Thaumaleidae)

Taxonomic group

Family: Thaumaleidae

Diagnostic features

The Thaumaleidae is a little known family of true flies with freshwater larvae. They resemble chironomid midges, but the prolegs at each end of the body are unpaired unlike chironomids. They have a snout-like head similar to the forcipomyids (but the latter have paired prolegs). Thaumaleids also have spiracles (breathing pores) on the thorax.

Typical habitats

Thaumaleids are not often recorded in stream surveys because they usually inhabit seepages and splash zones (habitats not sampled during most stream studies).


We assume they graze on the biofilms of splash zones, as is the case with overseas species.

Indicator value

  • Hard bottom: 9
  • Soft bottom: 8.8

The tolerance values (ranging from 0 to 10) give an indication of which are the sensitive taxa (values of 8 or more) and which are the tolerant taxa (values of 3 or less). For more information see: Indicator species

Thaumaleids are usually found along the margins of rapids and waterfalls, typically in bush covered areas where water quality is expected to be good. They have high tolerance values of 9 (hard bottom sites) and 8.8 (soft bottom sites).