The dobsonfly or creeper, is New Zealand’s largest stream insect and looks a bit like a centipede. It is also referred to as a ‘toe-biter’ because of its pincer-like jaws which can give a painful nip. The larvae are around 25 millimeters long and prey on mayfly larvae. They are an important part of the trout diet especially in the larval form.

Dobsonflies spend most of their lives in the larval form and take several years to mature. They prefer stony clear water.

Larva

The larval form of the dobsonfly is the most common stage that is of interest to trout. They are recognised by their legs and the sharp pincers they have which can give a sharp nip to anyone wading with bare feet.

In spring the dobsonfly larva crawl out of the water and under bank-side rocks so they can pupate.  With spring rain, water levels rise and many of the creepers are washed out from under the rocks where the trout are waiting for them.

Adult

The adult form is one of New Zealand's largest aquatic insects. They are seldom seen during the day but become very active at night. They are not a common part of the trout diet however.

Imitating the larval form

Creeper trout fly patterns are an essential part of the fly box. These ugly aquatic nymphs are found throughout NZ though are most common in North Island waters where they make a sizeable proportion of the trouts diet. Anyone wading barefoot will at some time have found out why they are also known as toe-biters. Sizes 12 - 14