#plecoptera

(Sources - 1, 2, 3, 4)

Order: Plecoptera

Common Name: “stoneflies”

Families: 16 - Austroperlidae, Gripopterygidae, Diamphipnoidae, Eustheniidae, Leuctridae (“rolled-winged stoneflies”), Taeniopterygidae (“winter stoneflies”), Scopuridae, Capniidae (“small winter stoneflies”), Nemouridae (“forestflies”), Notonemouridae (“southern stoneflies”), Peltoperlidae (“roach-like stoneflies”), Pteronarcyidae (“giant stoneflies”), Styloperlidae, Perlidae (“common stoneflies”), Chloroperlidae (“green stoneflies”), and Perlodidae (“stripetail and springfly stoneflies”)

Anatomy: nymphs (image 4) are aquatic with external gills (location varies between species); chewing mouthparts; multiple-segmented antennae; 2 large compound eyes and 2 or 3 ocelli; long, relatively soft abdomen; 2 long cerci on the tip of their abdomen; adults are similar to the nymphs, but with no gills and two pairs of membranous wings which fold flat over their back (image 1 and 3); some adults retain remnants of nymphal gills and some species are entirely wingless (image 2)

Diet: submerged leaves and algae as nymphs, some are hunters of other aquatic arthropods; adults are herbivorous, or do not feed at all

Metamorphosis: hemimetabolous

Habitat: nymphs/naiads are aquatic, living in the benthic zone of well-oxygenated lakes and streams; a few New Zealand species are terrestrial in moist environments; adults are not strong fliers and thus generally stay near the area they emerged from; found worldwide, except Antarctica

Evolved in: Late Carboniferous

(source)

Propaganda under the cut:

Juvenile hemimetabolous insects are called nymphs, and they look almost exactly like their adult counterparts. However, aquatic nymphs, called naiads, have a couple more differences due to living in a different environment.

For example, this blue-tailed damselfly nymph (Ischnura Elegans) has gills on the end of its abdomen.

Some insects that have naiads (aquatic nymphs) are dragonflies & damselflies (Odonata), mayflies (Ephemeroptera), and stoneflies (Plecoptera).

Northern Stone Agnetina capitata

A stonefly found in Canada and the United States.

You have subscribed to DAILY BUG FACTS

🪲

TODAY'S FACT IS

Did you know that the Otway Stonefly (Eusthenia nothofagi) is only found in the Australian Otway Ranges?

They are typically found in wet environments with plenty of beech and/or ash trees. Stoneflies in general are intolerant of water pollution so seeing these around water sources is a good indicator of the water's health.

🪲

Thank you for subscribing to DAILY BUG FACTS

Stonefly - Subfamily: Perlodinae

With special thanks to a dear friend of mine exploring the wilderness of Squamish, British Columbia, this video is the first (of hopefully many) of 2026. Keeping to their active season of early spring as also recorded in previous videos, the Stoneflies of Squamish have returned and this one is quite active! Although this individual appears to be on dry land, it isn't very far from a water source. Specifically, this insect was filmed near the Squamish River by Edgewater Park; a fine water source spend time developing as an aquatic nymph. According to my friend who recorded this video, the rocks filmed here are occasionally submerged completely by water which arrives in the form of rainfall and meltwater from on snow on B.C.'s mountains. If that's the case, this is the perfect environment for Stonefly nymphs to complete their metamorphosis into a winged adult. They would be able to cling onto these stones or nearby man-made structures when the water rises, and then emerge as it recedes and conditions become warmer and drier. My friend also noted that while the stone parts exposed to the sun were radiating heat, the water was freezing. While such temperatures would be harmful to most insects, Plecopterans can have adaptations against ice cold conditions such as chemicals within their hemolymph (blood) that act as an antifreeze, or even simple strategies such as insulating themselves from cold within riverbed materials. If successful and uneaten, the result is a fit adult Stonefly with energy to spare as it searches for a mate. Although now equipped with braided-veined wings, it usually will not fly far from its emergence site.