Caddisfly

Caddisfly facts

Scientific name: Trichoptera

Diet: Aquatic plants and decaying organic matter

Predators: Birds, fish, small mammals and other invertebrates

Size: 2mm-3cm

Weight: 0.01-7.22mg

Lifespan: A few weeks to several months

About caddisflies

There are about 200 species of Trichoptera, an order of small insects that range from 2mm to 3cm in size. Some of the most common species you’ll find by our canals are the cinnamon sedges (Limnephilus lunatus), grousewing caddisfly (Mystacides longicornis) and long horn sedge (Oecetis ochracea).

Caddisfly and our canals

Caddisflies are water-loving insects and are typically found around slow-flowing rivers, ponds and canals. While most live underwater as larvae, the Enoicyla pusilla is given the name ‘land caddis’ for its unusual habit of living in woodlands among leaf litter. Caddisflies build their own shelters, which are cases made of the habitats they live in, like stone, sand, leaves or twigs, and spun together with their own silk.

How to identify a caddisfly

As adults, caddisflies look a lot like moths. But unlike moths, they fold their wings back. These are also covered in fine hairs.

You might struggle to identify individual adult species – some have long antennas, while others, like the grousewing caddisfly, have patterned wings. As larvae, their unique casing makes them easier to tell apart.

What do caddisflies eat?

Most larvae caddisflies are herbivores, feeding on aquatic plants, algae and other decaying organic matter in or near their freshwater habitats. Some species are predatory, eating smaller aquatic invertebrates.

Some adult species feed on nectar and are important pollinators.

How do caddisflies breed?

Adults only live for a few weeks, and their main purpose is to breed. The females release pheromones to attract males. The eggs are laid near water and usually hatch after a few weeks – usually in the autumn. Some species perform courtship displays to attract their mates.

Where do caddisflies live?

Caddisflies are found in all kinds of wetlands – from streams and ponds to our canals. As adults, they typically live on land but are usually still found near water. You’re likely to spot caddisflies on any of our waterways.

Land caddisflies, who are terrestrial even as larvae, are often found in the woodlands in the West Midlands.

Tips to spot caddisflies

Caddisflies are small and often blend into their surroundings, so they’re usually hard to spot. Look for their distinctive casings near water at dusk – when they’re most active.

Other species to look out for