Insect Order Lepidoptera (Moths)

Mayflies

Caddisflies

Stoneflies

Taxonomic Navigation -?-

Kingdom Animalia (Animals)

» Phylum Arthropoda (Arthropods)

» Class Insecta (Insects)

» Order Lepidoptera (Moths)

Family in Lepidoptera
GeometridaeInchworms	1	7

12 families aren't included.

Common Name

Match	Common Name
	Moths

Pictures Below ↓

The order Lepidoptera includes both butterflies and moths, but moths are the most important to the angler because so many species spend part of their lives underwater. These aquatic species are similar in many ways to caddisflies.

Many species, of course, are not aquatic at all.

Hatching Behavior

The pupae of aquatic moths turn into adults underwater in their cocoons, so they are not worth imitating. The emerging adults, swim away from their pupal cocoons and are vulnerable to trout until they crawl or fly away from the water.

Egg-Laying Behavior

Time Of Day: Usually dusk or nighttime

Mirroring the behavior of caddisflies, aquatic moths may lay their eggs on the surface or dive underwater to lay them on the bottom. The diving species are the most common, and they are especially vulnerable to trout. Anglers frequently see the adults in our flashlights as we leave the stream for the night, and Swisher and Richards wrote in Selective Trout:

Because almost all of the action is at dusk and later, anglers don't realize how prolific these insects really are.

Larva & Pupa Biology

Diet: Algae and plankton
Shelter Type: Some build silk shelters.

Aquatic moth larvae live in a variety of ways underwater, including building silken shelters. Their appearances vary tremendously in size, color, and form, but they are a rare find in most places. In all my nymph sampling I have never yet turned up an aquatic moth larva.

1 Moth Specimen:

Geometridae (Inchworms) Moth Larva

View 6 PicturesI caught this inchworm lowering itself to the surface of a trout stream from its silk thread. I saw a couple others floating on the surface, so it's likely the trout were familiar with them.

Region: Poconos

Collected May 29, 2007

Added Jun 4, 2007

1 Streamside Picture of Moths:

View Full Size (2.7X larger)

In this picture: Moth Family Geometridae (Inchworms).

RegionUpper Midwest

Date TakenJun 7, 2006

Date AddedJun 30, 2006

CameraCanon EOS 20D

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Jargon Defined:

Larvae: Many classes of aquatic insects, such as caddisflies, midges, craneflies, dobsonflies, alderflies, and many more, are known as "larvae" rather than "nymphs" in their juvenile stages. They have mostly soft bodies rather than hard exoskeletons. These insects also advance through a "pupa" stage before reaching adulthood.

Nymph: The juvenile, underwater stages of mayflies, stoneflies, dragonflies, and damselflies and other aquatic insects whose juvenile stages are covered by hard exoskeletons. The word can also refer to the fishing flies which imitate these creatures, in which case it is used as a blanket term for flies imitating any underwater stage of an invertebrate (except for crayfish and leeches).

Pupae: Any insect which spends most of its juvenile lifetime as a larva first becomes a pupa for a time before emerging as a fully grown adult. Depending on the species, the pupal form can be very important for fly fishermen to imitate.

Useful References:

LaFontaine, Gary. 1981. Caddisflies. The Lyons Press.

Swisher, Doug and Carl Richards. 2000. Selective Trout. The Lyons Press.