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Arthropod Class Insecta (Insects)

Pictures Below
Nearly a million species of insects have been described by entomologists. I have left several of them off of this site, just to save time, but I've tried to include all the main aquatic insects trout eat in North America.

This site focuses on aquatic insects, of which the most important are mayflies (Ephemeroptera) and caddisflies (Trichoptera). Stoneflies (Plecoptera) come in third, a position arguably challenged by the many two-winged true flies of the Diptera order, which includes midges and craneflies. I've also included some terrestrial (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.) insects which I've found on or near trout streams. Terrestrials (Terrestrial: Insects which live on land and are fed on by trout only when they incidentally fall into the water are known as "terrestrials" to fly anglers, and they're very important in late summer.) like ants, beetles, and grasshoppers are an important food source for trout in many places, especially during the summer months.

Aquatic insects do not live their entire lives in the water. Instead, they grow for a year (give or take quite a bit) as nymphs or larvae underwater, and then they emerge into air-breathing winged insects for a short while to mate and die. There are many variations on this theme.

The most important aquatic insects for fly fishermen are mayflies, stoneflies, caddisflies, and midges. Mayflies and caddisflies are the most discussed by angler-entomologists, because it's so useful to closely identify them. The behavior of their species guides the behavior of feeding trout, and an angler who understands the lifecycle of a particular species has the upper hand when it's hatching. This is not so important for stoneflies and midges, because their hatching behavior is less variable.

Pictures of 1231 Insect Specimens:

Specimen Page:1234...124
Neophylax (Autumn Mottled Sedges) Caddisfly AdultNeophylax (Autumn Mottled Sedges) Caddisfly Adult View 20 PicturesThis large caddisfly looks really neat close-up.
Collected September 19, 2006 from Mystery Creek #43 in New York
Added to Troutnut.com by Troutnut on October 4, 2006
Specimen Page:1234...124

114 Underwater Pictures of Insects:

Underwater Photo Page:1234...13
Hundreds of cased caddisfly larvae live on this log in a small brook trout stream.  In this picture: Insect Order Trichoptera (Caddisflies). From Eighteenmile Creek in Wisconsin.
Hundreds of cased caddisfly larvae live on this log in a small brook trout stream.

In this picture: Insect Order Trichoptera (Caddisflies).
Date TakenApr 14, 2004
Date AddedJan 25, 2006
AuthorTroutnut
Several Baetidae nymphs line up on a rock.  In this picture: Mayfly Family Baetidae (Blue-Winged Olives). From Mongaup Creek in New York.
Several Baetidae nymphs line up on a rock.

In this picture: Mayfly Family Baetidae (Blue-Winged Olives).
Date TakenApr 19, 2006
Date AddedApr 22, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
This is a close-up underwater view of a stillborn Ephemerella subvaria (Henrickson) female dun.  In this picture: Mayfly Species Ephemerella subvaria (Hendrickson). From the East Branch of the Delaware River in New York.
This is a close-up underwater view of a stillborn (
This stillborn Ephemerella subvaria dun is trapped in its shuck.
This stillborn Ephemerella subvaria dun is trapped in its shuck.
Stillborn: In fly fishing, a stillborn insect is one which got stuck in its nymphal or pupal shuck during emergence and floats helplessly on the surface instead of flying away. It is a specific class of cripple, although it is sometimes used interchangeably with that term.
)
Ephemerella subvaria (Henrickson) female dun.

In this picture: Mayfly Species Ephemerella subvaria (Hendrickson).
Date TakenApr 19, 2006
Date AddedApr 22, 2006
AuthorTroutnut
CameraPENTAX Optio WPi
Underwater Photo Page:1234...13

Recent Discussions of Insecta

Possible ID 2 Replies »
Posted by Sreyadig on Apr 11, 2021 in the species Apobaetis futilis
Last reply on Apr 19, 2021 by Crepuscular
In searching for nymphs in my small stream in northern Maryland, 500 yards from the PA line, I came across a 2 tailed mayfly that was not a of the Epeorus genus.

It was in a fast riffle section along with Epeorus nymphs. This was about 3/8” in overall length including tails. Darker straw coloration with dark brownish black wing cases that were pronounced in color and shape. Biggest factor was the tails. Median caudal filament was truncated, very small compared to the outer pair. Not even sure if tail/ caudal filament should be used to describe. In my books the closest thing is the Pseudocloeon futile. Which is an old taxonomic name I’m finding out.

This find seems rare in my area and experience. Hopefully I can get a photo...
ReplyHexagenia orlando 5 Replies »
Posted by Curtis on Feb 29, 2008 in the genus Hexagenia
Last reply on Nov 20, 2020 by SALTYQUILL
Does anyone have any hatch dates for hexagenia orlando in the Central Florida area? Several lakes near me have populations and I am gathering data. I have photos and one hatch record.
ReplyYea...
Posted by Imaxfli on Oct 23, 2020 in the species Ephoron leukon
Me too looking for photos or better yet, video of matching. These things seem to pop outa the water like no other ......
ReplyTrico emergers 6 Replies »
Posted by Bwoklink on Jul 14, 2018 in the genus Tricorythodes
Last reply on Sep 11, 2020 by Martinlf
Anyone have experience fishing Trico emergers patterns? I’ve had experience fishing the winged and spinner stage, but haven’t heard of anyone fishing emergers during the early morning female hatch. Anyone used emerger patterns and if so would you might sharing which ones you have found effective?
ReplyPMD Spinner - Egg sack color? 20 Replies »
Posted by Wbranch on Jan 26, 2010 in the species Ephemerella excrucians
Last reply on Aug 18, 2020 by Troutnut
Do any of you entomologist types know the true color of the PMD spinner? Dorothea or excrucians. Where I fish in MT there are huge spinner falls, many spents are on the water in the morning and others fall again at various periods during the day. I'd like to tie some with egg sacks as I saw many in July but forgot what color they were. Thanks.
Reply
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