Insect · GBIF taxon 1729944
Eastern Dobsonfly
Corydalus cornutusAlso known as Hellgrammite, King Bug, Goober Bug
Eastern dobsonflies are impressive aquatic insects famous for the oversized, sickle-like mandibles of adult males. Their fierce larvae, known as hellgrammites, spend several years underwater in fast-flowing streams as formidable predators before metamorphosing into winged adults. Adults emerge in midsummer, living only a week or two to mate along clean riverbanks and night-lit walls.
NocturnalAquatic LarvaeStriking Mandibles
—observations
—countries
—peak records
Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Diet & prey
- Mayfly Nymphs
- Caddisfly Larvae
- Stonefly Nymphs
Predators
- Freshwater Fish
- Bats
- Insectivorous Birds
ThreatsWater pollution, stream siltation, and night light pollution
HabitatsClean rocky streams, rivers, and adjacent riparian forests
Life span2–5 years (larvae); 1–2 weeks (adults)
Size / weightNot available
Classification
- FamilyCorydalidae
- SpeciesCorydalus cornutus
Range data is not available yet.
Interaction riskLow
- Low
- Moderate
- High
- Very high
- Why interaction risk is low
- Females and larvae deliver a sharp, painful pinch if grasped; observe safely without handling.
- Why it is dangerous
- Females and aquatic hellgrammites possess short, powerful jaws capable of delivering a painful pinch that can break skin.
- How to recognize a risky encounter
- Look for large dark greyish-brown bodies, heavily veined translucent wings, and prominent jaws near swift streams.
- What to do
- Observe from a safe distance under outdoor lights or along riverbanks; avoid picking them up by hand.
Responsible observation
- Light Trapping: Search illuminated walls near clean rivers on warm midsummer nights.
- Handling Caution: Keep fingers well clear of short, sharp female mandibles and aquatic larvae.
- Stream Health Indicator: Finding larvae under river stones signals clean, oxygenated water.
Close Relative Family Member Order Relative
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