At 4 cm (1.6 in) Eusthenia spectabilis is the largest member of the genus and emerges later than other similar species.

Sexual dimorphism is found in all life stages with females being larger in both adult and nymph forms the species is perhaps best identified from it external genitalia, males having short and untoothed epicrot whilst females having a simple genital plate which are distinctive compared to other members of Eusthenia.

[2]: 115 As with most stonefly E. spectabilis is a completely aquatic carnivore at juvenile stages, developing into a less voracious winged, ephemeral adult.

[2]: 119  Naiads will emerge roughly after year then, climbing into the riparian zone to moult into adults.

E. spectabilis was the first freshwater invertebrate recorded to produce metallothionein this was in response to high cadmium concentrations[5] This Plecoptera related article is a stub.