Wednesday, July 17, 2013

EPT List: Summer insects in the Rivanna

It's mid-July, and I've still not made it to the Rivanna: it remains high, fast, and muddy.  Maybe next week or the week after.

I mainly look in the Rivanna during the summer since the water is too high or too cold during the rest of the year.  I'd really like to see what I would find there in late winter and spring.  But for the moment, this accounting will only list summer insects.  I've seen 7 species in the Rivanna that I've not seen anywhere else -- as best as I can remember: the small minnow mayflies Heterocloeon petersi (pictured above) and Iswaeon anoka; the little stout crawlers (Tricorythodes); the common stonefly Agnetina annulipes (though I may have seen this one at Buck Mt. Creek as well); the tiny micro caddisflies, family Hydroptilidae; Long-horned caddisflies, Nectopsyche exquisita; and the Emerald dragonflies, Neurocordulia obsoleta.

Dragonflies and damselfies are common in the Rivanna during the summer, as are common netspinners (Hydropsyche venularis and Hydropsyche rossi).   Surprisingly, there are Giant stoneflies in this big river, but in the summer, they're too small to identify to the level of species.

          EPT Species List for the Rivanna River in Summer

I. Ephemeroptera (Mayflies)

1. Baetidae (Small minnow mayflies)

1. Acentrella turbida
2. Baetis intercalaris
3. Baetis pluto
4. Heterocloeon curiosum
5. Heterocloeon petersi
6. Iswaeon anoka
7. Labiobaetis propinquus

2. Heptageniidae (Flatheaded mayflies)

1. Heptagenia marginalis
2. Maccaffertium modestum
3. Stenacron interpunctatum

3.  Ephemerellidae (Spiny crawler mayflies)

1. Serratella serratoides

4. Leptohyphidae (Little stout crawler mayflies)

1. Tricorythodes

II. Plecoptera (Stoneflies)

1. Taeniopterygidae (Large winter stoneflies)

2. Taeniopteryx burksi/maura (in the fall)

 3. Perlidae (Common stoneflies)

1. Acroneuria abnormis
2. Agnetina annulipes
3. Agnetina flavescens

4. Pteronarcys (Giant stoneflies)

1. Pteronarcys dorsata

III. Trichoptera (Caddisflies)

*1. Hydroptilidae (Micro caddisflies)

1. Hydroptila (?)

2. Philopotamidae (Fingernet caddisflies)

1. Chimarra

3. Hydropsychdae (Common Netspinners)

1. Hydropsyche rossi
2. Hydropsyche venularis

4. Brachycentridae (Humpless case-makers)

1. Brachycentrus appalachia

5. Lepidostomatidae

1. Lepidostoma

6. Leptoceridae (Long-horned case-makers)

1. Nectopsyche exquisita
2. Oecetis

IV.  Odonata (Dragonflies and Damselflies)

1. Narrow-winged damselflies (Coenagrionidae) -- genus Argia
2. Broad-winged damselflies (Calopterygidae)  - Haeterina americana
3. Clubtail dragonflies (Gomphidae) -- Hagenius brevistylus
4. Emerald dragonflies (Corduliidae) -- Neurocordulia obsoleta

Photos of some of the common -- and some of the uncommon -- summer insects in the Rivanna.

1. Small minnow mayfly, Iswaeon anoka.  (Uncommon species)

2. Small minnow mayfly, Heterocloeon petersi.  (Also uncommon)

3. Small minnow mayfly, Heterocloeon curiosum.  (Common)

4. Little stout crawler, genus Tricorythodes

5. Long-horned caddisfly, Nectopsyche exquisita


1. Broad-winged damselfly, Haeterina americana

2. Narrow-winged damselfly, genus Argia

3. Club-tailed dragonfly, Hagenius brevistylus

4. Emerald dragonfly, Neurocordulia obsoleta


The Rivanna River at Crofton.

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