Caddisflies

• Phylulm Arthropoda (Jointed Legs)
• Class Insecta (Six Legs)
• Order Trichoptera ( "Hairy Wings")

Other Names

• Tricopterans

Larvae Appearance

• Larvae resemble caterpillars with a dark brown head
• Hard, dark-coloured plates are located behind the head
• Jointed legs are located immediately under the head
• Bodies are brown, bright green or cream-coloured
• May have feathery gills under the abdomen
• May have hooked, fleshy or feathery extensions (prolegs) at their back end
• Three types of larvae include case builders, free-roamers and net-spinners

Case Building Larvae

• Sometimes hide inside a protective case made of stones or twigs
• Drag their cases with them and hide inside from danger
• Pull the cases slowly and awkwardly with the use of their front legs
• Case builders stick only their hard head, thorax and legs out the front end
• Cases are held together by glue secreted from salivary glands or anal glands
• Each species has a characteristic style of case materials, pattern and shape
• Cases are renovated and made longer and wider as the larvae grow

Net-Spinning Larvae

• Some larvae build small silky nets to trap passing food
• Net-spinning larvae live in or near their nets
• Nets are attached to rocks and may include stones or twigs

Larval Feeding Types

• Carnivores, herbivores or omnivores
• Free-living caddisfly larvae with narrow heads are predators on insect larvae, crustaceans and worms
• Omnivores eat algae, plants, larvae and worms
• Net-spinners with wide heads are filtering collectors
• Case-builders can be filtering collectors, gathering collectors, shredders or scrapers

Pupation

• All larvae eventually build a case to pupate
• Larvae seal themselves inside cases for pupation
• After maturing, the pupae quickly rise to the surface to emerge as adults
• Pupae may be propelled to the surface by escaping gas

Adult Appearance

• Adult caddisflies resemble moths in shape, colour and fluttering flight
• Adults have four large, fuzzy, brown wings
• Large, obvious wings are folded upright like a tent when at rest
• Looks triangular when viewed head-on with wings folded
• Two very long antennae
• Adults that land on rocks, boats or people scramble for a place to hide

Adult Behavior

• Attracted to lights
• Weak mouthparts capable of ingesting liquids only

Aquatic Habitat

• All types of water, moving or still
• In fast water, cases are built from sand and small stones
• In slower or still water, the cases are built from plant debris

Reproduction

• Complete metamorphosis includes egg, larvae, pupae and adult stages
• The underwater stages may last one to three years
• Adults live up to two or three weeks
• Some flying females dive underwater to lay eggs directly on the bottom
• Some flying females flutter along the water surface to lay eggs

Predation

• Trout love to eat caddisfly larvae and pupae
• Trout rise violently and splash when chasing surfacing pupae
• Trout feeding on larvae eat the case together with the insect
• Larvae are eaten by predaceous diving beetles

Larval Pollution Tolerance

• Caddisfly larvae are moderately tolerant of pollution and heat
• Large numbers of caddisfly larvae may indicate fair water quality or warm water
• Caddisflies may become more common as an effect of global warming