Blue-winged Olives
Baetis
Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
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This one seems to tentatively key to Holocentropus, although I can't make out the anal spines in Couplet 7 of the Key to Genera of Polycentropodidae Larvae nor the dark bands in Couplet 4 of the Key to Genera of Polycentropodidae Larvae, making me wonder if I went wrong somewhere in keying it out. I don't see where that could have happened, though. It might also be that it's a very immature larva and doesn't possess all the identifying characteristics in the key yet. If Holocentropus is correct, then Holocentropus flavus and Holocentropus interruptus are the two likely possibilities based on range, but I was not able to find a description of their larvae.
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True Bug Family Notonectidae (Backswimmers)
Backswimmers are often important to trout, especially in ponds. They're one of the insects which usually doesn't factor into a fly angler's decisions at all, but it pays to be aware of them because in just-so situations the trout eat nothing else.
Be careful handling them--they have a painful bite.
Be careful handling them--they have a painful bite.
Where & when
In 954 records from GBIF, adults of this family have mostly been collected during July (22%), August (17%), June (11%), September (10%), October (8%), April (8%), May (6%), and March (6%).
In 52 records from GBIF, this family has been collected at elevations ranging from 23 to 19685 ft, with an average (median) of 2382 ft.
Family Range
Egg-Laying behavior
The adults breathe air. Normally they rest upside down at the water's surface with part of their abdomen sticking up just out of the water to breathe, but they can dive for extended periods carrying an air bubble with them. They are able to leave the water and fly around.Nymph biology
Diet: Other insects, including other backswimmers
Specimens of Backswimmers:
2 Adults
Notonectdiae adults can leave the water and fly off whenever they wish. This specimen was caught when it landed on my car. These adults are one of the few aquatic insects that can protect itself with a strong beak.
Start a Discussion of Notonectidae
References
- Schwiebert, Ernest G. 1955. Matching the Hatch. MacMillan Publishing Company.
True Bug Family Notonectidae (Backswimmers)
Taxonomy
3 genera (Buenoa, Martarega, and Notonecta) aren't included.