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Guide to New Zealand's freshwater invertebrates
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.
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.
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).