T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Mayfly (Ameletopsis perscitus) Yellow dun

Kingdom:   Animalia
Phylum:     Arthropods
Class:        Insecta
Order:       Ephemeroptera
Family:      Ameletopsidae
Genus:      Ameletopsis
Species:     A. perscitus
Binominal name:  Ameletopsis perscitus
Common names: Yellow dun, Sulphur dun.

Ameletopsis perscitus it is the only known species in this genus and is endemic to New Zealand. 
This rather uncommon mayfly is distributed throughout the country from the Southland hill streams to Fiordland’s mountain streams and up the West Coast and as far as the upper North Island’s rivers.
This mayfly imago (the last stage an insect attains during its metamorphosis) is 18 mm in length. The head is yellow; the thorax is a light yellow with brown areas dorsally and ventrally. The abdomen is a bright yellow except for its top surface which is a fawn colour. The wings, legs and wings are yellow. This winged stage appears from the end of December to March. The adults are short-lived.
The larva of Ameletopsis perscitus has a body length of 16 millimetres and cerci around five millimetres. It is New Zealand only carnivorous mayfly larva and one of very few in the world. This predatory nymph lives in stony streams and rivers. It has an enlarged large skull-like head.

Photo courtesy of Dean Bell a New Zealand fly fishing guide.  http://www.deanbellflyfishing.co.nz 

It is the only yellow mayfly in New Zealand. This photo is courtesy of James Cooper.  https://www.facebook.com/Bugsupclose/

Photo of Ameletopsis perscitus nymph courtesy of David Wilson of Nature Watch.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0