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Life-cycle
Adult to: - Egg to: - Larva to: - Pupa to: - Adult
Life-cycle stage 1 -The adults
Colour are blacks, browns, greys and oranges. They look like moths, which are the closest relatives of caddis amongst other insects.
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| Goera pilosa |
Most adults live for a few days or up to a week or so. They can drink water and feed on flowers with open nectaries, such as those of hogweed. Most species have adults that fly in the early part of the night, but they are easily disturbed into flight during the day. There are some conspicuous day-fliers.
Life-cycle stage 2 - The eggs
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| Egg masses of the cased caddis Brachycentrus subnubilus |
Adults of cased caddis usually lay eggs in large groups within a jelly blob. Cased caddis eggs groups can be quite noticeable.
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| Egg mass of the caseless caddis Philopotamus montanus |
Adults of caseless caddis usuallly lay eggs in small groups, or strings or sheets, closely stuck to a rock or stick and covered by a thin layer of jelly. Caseless caddis eggs are rarely noticed.
Life-cycle stage 3 - The larvae
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| Larva of Ceralcea dissimilis |
All caddis spend the majority of their life-cycle in the larval stage. They are able to produce silk which most species use to construct a protective case for themselves often incorporating stones, plant material sand etc.. Caddis larvae are distinguished from other insect larvae that have jointed thoratic legs by the presence of two anal prolegs, each bearing a single curved hook.
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| Posterior end hooks of Tinodes sp. |
Life-cycle stage 4 - The pupae
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| Shelters detached to reveal pupae (shelters have no underside) |
When the larva is fully grown it prepares a pupation shelter. Cased caddis fix their larval case to a firm object and make a grill for each end to exclude predators. Caseless caddis make a purpose built rough shelter of stones and /or vegetable debris stuck to a fim object.
The larva settles into a special stance and after a few days sheds its skin to reveal the pupal skin that has formed beneath. Over about two weeks the adult forms inside the pupal skin.
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| Rhyacophila cocoon detached from shelter |
Rhyacophila cocoons often get detached from their shelter and end up in the tray.
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Escape of the adult
When fully developed the adult operates the mandibles of the pupal skin to cut a hole in its case or shelter. Still enclosed in the pupal skin it swims to the surface or bank. The skin splits and the adult quickly emerges. The concertinered wings expand rapidly and the adult flies off.
