SMOOTH-CASED CADDIS

Olinga feredayi

Most caddisfly larvae construct a case structure (below left) to protect and disguise the larval stage while still enabling them to remain mobile. Different groups of caddisflies can be distinguished by the different shapes and materials they use for their cases. Olinga caddis larvae build smooth cases that lack sand grains. The aperture of the case is straight to slightly curved, resembling a horn, and indeed it is also known as horn-cased caddis. This species is a very good water-quality indicator for hard-bottom streams.

Description: The rounded orange or red head of the larva (below right) is smooth and without hairs. There is a black mark on the side of the body behind the hind legs. Adults (male above left, female above right) are rather small with yellow and brown, very fringed wings.

Habitat and distribution: Common, and generally distributed throughout Aotearoa New Zealand in and around running streams. Larvae are most common in bush-covered, cold-water, stony streams.

Biology: The very active larvae climb on rocks in strong water currents. Before they pupate, inside their cases, they attach themselves to a rock, often in large groups, and close the upper end of the case. Adults are active in the evening at dusk, often being seen in swarms as they emerge simultaneously. Females carry their eggs at the end of their body before dispatching them in the water. An abundance of Olinga larvae indicates good habitat and water quality, particularly if mayfly and stonefly nymphs are also present.

Status in Aotearoa: Endemic