Trichoptera for the Novice Entomologist and the Trout Fisherman
The bundles of sticks crawling about in the water or small pieces of debris moving jerkily about on the bottom of a stream or shallow pond are caddisflies. These bits of debris are hollow cylindrical cases, composed of sand grains, gravel, pieces of leaves, and bark or twigs. Trichoptera, or caddisflies, are one of the largest groups of aquatic insects (Order Trichoptera, Class Insecta of the Phylum Arthropoda) closely related to the Order Lepidoptera (moths and butterflies). Remember your high school biology: Kingdom, Phylum, Class, Order, Family, Genus, species? The scientific name “trichos”means hair and “pteron” means wing.
Imagine you are a caddisfly that has been lolling in your case in the stream for almost a year and the urge to find a mate is just too much. So you pupate and then on a delightful summer evening you just cannot wait. So up to the surface you swim and BANG!!! You hit the water surface (meniscus). Then as Ken Thompson describes in Gary LaFontaine’s book “Caddisflies,” when the top part of the pupal thorax protrudes through the surface and splits open, a meniscus forms around it, creating an escape hole in the surface. The adult insect crawls through the hole, never even touching the water. Once the insect is on the water surface, its structural hairs and body surface are water resistant and keeps it floating until the adult body surface hardens and it flies away. The physical energy required to break through the water surface in human terms is equivalent to the amount of energy for a full-grown person to escape from being covered with three feet of soil.
The process of moving from the pupal case off the bottom through the water column as a pharate adult and airborne is one of the most vulnerable parts of the life cycle and our well-educated trout have learned this. So fisherman will tie flies to duplicate this stage.
Here are a few common names that you can use at this site:
Family APATANIDAE
- Early Smoky Wing Sedge - Apatania
Family BRACHYCENTRIDAE (tube-case maker)
- American Grannom – Brachycentrus
Family GOERIDAE
- Little Gray Sedge - Goera
Family GLOSSOSOMATIDAE (saddle-case maker)
- Little Tan Short - Horn Sedge – Glossosoma
Family HYDROPTILIDAE ( purse- case maker)
- Vari-Colored Microcaddis – Hydroptila
- Ring Horn Microcaddis – Leucrotricia
- Cream & Brown Mottled Microcaddis – Oxyethira
Family LEPIDOSTOMATIDAE –(tube-case maker)
- Little Plain Brown Sedge – Lepidostoma
Family MOLANNIDAE (tube-case maker)
- Gray Checkered Sedge – Molanna
Family POLYCENTROPODIDAE (net spinner)
- Little Red Twilight Sedge – Neureclipsis
- Dinky Light Summer Sedge – Nyctiophylax
- Brown Checkered Summer Sedge – Polycentropus
Family PSYCHOMYIIDAE (net spinner)
- Dark Eastern Woodland Sedge – Lype diversa
- Dinky Purple-Breasted Sedge – Psychomyia
Family UENOIDAE
- Autumn Mottled Sedge - Neophylax
Further Information
Adults are mothlike with four membranous wings, some are weak and others are strong flyers. They have a complete (holometabolous) metamorphosis, which means they go through the egg, larva, pupa, and adult stages. The caddisfly larvae are essentially caterpillar-like and the common name “caddis” was probably derived from their habit of constructing nets or cases.
Caddisfly larvae occur in numerous types of aquatic habitats – streams, ponds and lakes. These larvae are an important component of benthic freshwater ecosystems providing direct (or indirect) food for fish and other aquatic animals. The caddisfly larvae are best known for their nets, retreats, and portable cases that are architecturally well adapted for specific habitats. These larvae are categorized into five different groups:
Free-living forms ~ Larvae move freely until just before pupation – Rhyacophilidae found in rapid flowing streams are this form and by some are considered the most primitive.
Saddle-case makers ~ Larvae construct cases that resemble the shell of a turtle. – Glossosomatidae The cases are oval with the dorsal sides convex, the ventral side flat and the whole case composed of relatively large pebbles.
Purse-case makers ~ Larvae are free living until the last instar when they construct a purse-shaped or barrel-shaped case – Hydroptilidae (micro-caddisflies).
Net-spinners or retreat-makers ~ Larvae are sedentary and construct fixed retreats, often with capture nets. – Philopotamidae – Larvae of this type live in rapid streams and construct tubes with a large opening upstream (finger-net or silken-tube spinners). Psychomiidae and Polycentropodidae (trumpet-net). These two families have a wide range of habitats in rapid streams, rivers and lakes. Hydropsychidae Larvae of this group construct a case-like retreat of sand pebbles, or debris with a cup-shaped net facing upstream (true net-spinners).
Tube-case makers ~ Portable cases of tubular form are constructed of various shapes and many types of materials: bits of leaves, twigs, sand grains, pebbles etc.- Phryganeidae - The larval case is usually long and slender, composed of narrow strips of material glued together in a spiral. (large caddisflies) Limnephilidae - This family is often common in ponds and slow-moving streams (northern caddisflies). Odontoceridae - Larvae of this family are found in swift streams where they construct a cylindrical case of sand. Molannidae - These are the larvae of sandy bottoms and the case is shield-shaped. Helicopsychidae – a typical snail-shell shape. Leptoceridae - Members of this family construct long, slender tapering cases and often occur in lakes (long-horned caddisflies). Brachycentridae - Often have very distinctive cases such as the genus Brachycentrus with a log-cabin square design.
Lepidostomatidae are common in spring streams.
Goeridae larvae construct cases using small pebbles and gluing a large pebble to each side to act as ballast and Uenoidae also belong in this group.
Most North American caddisflies are univoltine, meaning that they have one generation a year but a few take two years (bivoltine). Larvae have five instars (stages). Pupation usually lasts 2-3 weeks. Adults emerge from their water habitat and become airborne becoming active at dusk when they search for a mate. Mating swarms occur in certain species and they may rely on swarm markers. Mating takes place on the ground or on vegetation. Oviposition behavior is varied with females depositing strands or masses of eggs.
LaFontaine, Gary 1981. Caddisflies Winchester Press. 336pp.
McCafferty, W.P. 1981. Aquatic Entomology. Sci. Books International. 448pp.
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