A good group of naturalists met on Crooked Creek at the Fred Berry Conservation Education Center this morning. I hope that others took pictures of the participants -- hopefully catching them at their photogenic best. I did not trust myself to do so. I mostly felt hot and sweaty and feared that others (feeling the same way) would not have wanted their pictures taken.
I don't think the bugs cared! Here area few good pictures taken with my Olympus TG-3 in close-up mode. Sharon Holland helped me out by snapping the best of these photos.
I uploaded some of them to Gemini AI for confirmation of ID. I hope you find Gemini's commentary as interesting as I did.
This insect is a mayfly (order Ephemeroptera). Based on its dark body color and completely transparent, glassy wings, this specimen is in its final adult stage, known as an imago or "spinner". [1, 2]Key Characteristics Visible in the Image
- Wings: The large, heavily veined, triangular forewings are completely clear. Mayflies are unique because they have two flying adult stages; earlier sub-adults (called "duns") have cloudy or smoky wings, whereas sexually mature adults ("spinners") have clear, shiny wings. [1, 2]
- Body Shape: A dark, segmented abdomen paired with a distinct thorax and compound eyes. [1, 2]
- Tails (Filaments): Though clipped or partially obscured against the background surface in this specific angle, mayflies are well known for the long, hair-like tails that extend from the end of their abdomen. [1, 2]
Behavior and FactsMayflies are entirely harmless insects. They do not bite, sting, or carry diseases, and the adults do not even have functional mouthparts to eat. They spend the vast majority of their lives (months to years) underwater as nymphs. Once they sprout wings and leave the water, adults live anywhere from a few hours to a couple of days purely to mate and lay eggs. Finding them around is a great indicator of a clean, healthy, and unpolluted nearby freshwater source. [1, 2, 3, 4]If you want to narrow down the specific group or match a fishing hatch, let me know:
- What is its approximate size (excluding the tail)?
- Did you find it near a specific body of water (like a stream, large river, or lake)?
You sent: 1 image and said: Identify insect
Identify insect3:01 PMThis insect is a mayfly nymph (order Ephemeroptera). This is the aquatic, juvenile stage of the winged adult mayfly you shared earlier.Specifically, its robust body, stocky legs with dark zebra-like bands, and flattened head strongly resemble a nymph from the spiny crawler mayfly family (Ephemerellidae) or a closely related flat-headed mayfly family (Heptageniidae). [1, 2]Key Characteristics Visible in the Image
- Developing Wing Pads: The dark, raised sections on its thorax (upper back) are wing pads, where its future flying wings are actively growing.
- Leg Banding: The prominent alternating light and dark bands on its legs are typical camouflage markers for clinging to rocks and blending into riverbeds.
- Abdomen and Tails: The tapered abdomen typically ends in three distinct, hair-like tails (filaments), though they appear tightly bunched or partially clipped in this view.
Behavior and Ecological RoleThese nymphs live completely underwater—usually clinging to rocks, gravel, or submerged wood in fast-flowing streams and rivers. They feed mainly on algae and organic debris. Because they are highly sensitive to chemical pollution and low oxygen levels, finding these nymphs is a reliable indicator of excellent, pristine water quality. They are also a primary food source for freshwater fish like trout, making them heavily studied by fly-fishers.Did you find this nymph in the exact same location or water source as the adult mayfly? If you are tracking a specific aquatic habitat, sharing the general region can help narrow down the exact genus.You said: It does not seem to have the gills
It does not seem to have the gills3:02 PMYou have an excellent eye! The lack of obvious, leaf-like gills fringing the outer edge of the abdomen is exactly what makes identifying this nymph tricky. However, it still fits perfectly into the mayfly order due to its anatomy.There are two primary reasons why the gills are not standing out in this image:1. Dorsal Gill Protection (The Spiny Crawler Design)If this is a spiny crawler mayfly nymph (Ephemerellidae), its gills are structured very differently from other mayflies. Instead of sticking out wide to the sides, their gills sit flat on top of their abdominal segments. [1]
- For genera like Eurylophella, the first pair of abdominal gills is modified into hard, protective plates (called operculate gills). These act like a tiny shield or turtle shell, resting over the back to completely cover and safeguard the delicate, feathery breathing gills underneath. This specialized adaptation prevents their breathing organs from getting clogged with mud or crushed when crawling under tight river stones. [1, 2]
2. Dislodged or Damaged GillsMayfly nymphs are fragile. When they are handled, caught, or exposed out of the water onto a dry surface, their delicate abdominal gills can easily flatten flush against the body, shrivel, or break off entirely.Why It's Still a Mayfly Nymph (and Not a Stonefly)When people see a river nymph without apparent abdomen gills, the immediate alternative guess is usually a stonefly nymph. However, your specimen has features that rule a stonefly out:
- The Wing Buds: The large, dark, parallel wing pads on its thorax curve downward over the top of the abdomen, which is a classic mayfly trait. Stonefly wing pads typically sit angled outward like chest plates.
- The Leg Layout: Its legs are tucked tucked vertically and forward tightly underneath its body.
If you still have the nymph or want to confirm the match, look closely at the very tip of its tail:
- Does it look like it originally had three tails bunched together? (Mayflies almost always have three, whereas stoneflies strictly have only two).
Show allYou sent: 1 image and said: Identify insect
Identify insect3:16 PMThis insect is a dragonfly nymph (specifically the cast-off skin or exoskeleton, known as an exuvia).The elongated, cylindrical body shape and the prominent spines on its head indicate it belongs to the Aeshnidae family, commonly known as the darners or hawkers.Key Characteristics Visible in the Image
- The Mask/Mouthparts: The wide, flattened structures extending forward from the front of the head are part of its modified lower lip (labium). In live nymphs, this acts as a spring-loaded mask used to ambush and capture prey underwater.
- Head Spines: The distinct, sharp horn-like projections protruding forward near the antennae are a defining structural characteristic of certain darner genera (such as Basiaeschna, the fawn darner).
- Elongated Abdomen: Unlike the broad, flat bodies of skimmer dragonfly nymphs, darners have a long, streamlined, tube-like abdomen built for actively climbing vegetation.
Behavior and Life CycleDragonfly nymphs are formidable aquatic predators. They spend months to years underwater eating other insects, tadpoles, and even small fish. When it is time to become an adult, the nymph climbs out of the water onto a rock or plant stem. Its back splits open, and the winged adult dragonfly emerges, leaving behind this hollow, straw-colored exoskeleton shell (exuvia).It looks like you are documenting a fascinating lifecycle or sampling a specific freshwater site! Are you monitoring a local stream or pond, or are you collecting these for a fly-fishing hatch guide?You sent: 1 image and said: Belly-up Dragonfly?
Belly-up Dragonfly?
3:19 PMNo, this dragonfly nymph is actually right-side up (dorsal view facing up), but it is a very unique type that naturally looks a bit "inside out" or distorted!This specimen is a nymph from the family Cordulegastridae, commonly known as a spiketail dragonfly (such as the Cordulegaster dorsalis, or Pacific spiketail).Why it looks "Belly-Up" or Strange
- The Massive "Mask" Face: Spiketails have an incredibly large, deeply cupped lower lip (labium) that acts as a predatory mask. Because it wraps all the way over the front and top of their face when resting, it creates a strange, hollowed-out look that can easily be mistaken for a broken underside or a gaping mouth. [1]
- Hairy Camouflage: Their legs and lower bodies are densely covered in tiny, stiff hairs (setae). In the wild, these hairs trap silt, mud, and organic debris. Now that it is sitting out of the water in a white tray, that caked-on dirt makes the top of its head and thorax look texturally rough and asymmetric. [1, 2]
- Dorsal Segments: You can see the distinct, overlapping armored plates on the back of its abdomen, confirming we are looking at its top side.
Behavior: The "Sit-and-Wait" SubmarineUnlike the streamlined darner nymph you shared before that climbs around on plants, spiketail nymphs are burrowers. They shimmy backward into loose sand or silt at the bottom of a stream until they are completely buried. Only their tiny, bead-like eyes stick out of the mud like a submarine periscope. They will sit perfectly still for weeks waiting for an unsuspecting insect or tadpole to swim by before launching their explosive jaw forward. [1, 2, 3]Is this specimen a live nymph that you found buried in the sand/silt, or is it another empty, casYou said: But it is found in an Ozark stream
But it is found in an Ozark stream
3:19 PMThat localized context fits perfectly. Knowing this was found in an Ozark stream pinpoints the geography exactly, meaning this is a nymph of the arrowhead spiketail (Cordulegaster obliqua) or the regional endemic Ouachita spiketail (Cordulegaster talaria). [1, 2]Spiketails are widely distributed across North America, but the Cordulegaster species in the Interior Highlands (the Ozark and Ouachita mountain regions) are specialized stream-dwellers. [1]Why an Ozark Stream is the Perfect Habitat for Them
- Clean, Spring-Fed Water: Spiketail nymphs require high-quality, cold, highly oxygenated running water. They are excellent biological indicators of a pristine stream ecosystem.
- Silt Accumulation: While Ozark streams are famous for gravel and limestone rocks, they feature slower-moving pool margins or backwaters where fine silt and sandy organic material pool up. That is where these nymphs bury themselves to ambush passing prey.
- Long Developmental Cycle: Because mountain streams stay quite cold, these nymphs grow slowly. A single spiketail nymph can spend up to 3 to 5 years living underwater in that stream bed before finally emerging as a winged adult. [1]
You have collected an amazing cross-section of clean-water stream life across these photos, from the highly sensitive mayflies to multiple diverse families of predatory dragonfly nymphs.Are you running a kick-net/sampling survey of the macroinvertebrates in this specific stream, or are you just exploring what is living in the riverbed? If you have more aquatic finds from the area, I would love to see them!
You said: List all the common names and scientific names of uploaded images from the stream
List all the common names and scientific names of uploaded images from the stream
3:23 PMBased on the images you uploaded from your Ozark stream sampling, here is the complete list of the insects you found, organized by their common and scientific names:
- Image 1 & 2: Spiny Crawler Mayfly Nymph
- Scientific Name: Family Ephemerellidae (possibly genus Drunella or Eurylophella)
- Image 3: Fawn Darner Dragonfly Nymph (Exuvia)
- Scientific Name: Basiaeschna janata (Family Aeshnidae)
- Image 4: Arrowhead Spiketail (or Ouachita Spiketail) Dragonfly Nymph
- Scientific Name: Cordulegaster obliqua or Cordulegaster talaria (Family Cordulegastridae)
Are you compiling these into a species checklist or water quality index for this stream? If you have any other macroinvertebrate photos from your sampling—like riffle beetles, helgrammites, or caddisflies—feel free to share them!______________________________
I did not upload and ask Gemini about my picture of a Dobsonfly (Hellgrammite) because I was sure of the ID.
