There are over 100 species of stonefly in New Zealand and spend much of their life in the larval form in clean freshwater streams.

The Stone Fly is an important part of the trouts diet with them being widely distributed throughout New Zealand waterways. In the larval stage they often resemble a Mayfly nymph but are generally larger and usually have well defined legs. Stone Fly trout fly patterns include green, black and brown stone flies. The Green Stone Fly is the largest and is best tied in sizes 8 - 12 with others in the 10 - 14 range.

Stoneflies should be fished with a dead drift as they are not active insects but do get washed down currents particularly in the faster waters of backcountry streams. The dry fly patterns are less used but are also very attractive to trout as they are larger and provide a good mouthful for the larger fish. Mainly found in the clear water of backcountry rivers and streams. The green stonefly is at its peak Nov-January ; Black Stonefly is best in Nov-March and the Brown stonefly throughout the year.

Generally found in gravel and stone bed rivers that are well oxygenated. In some backcountry streams where the water is clean they can make up the bulk of some trout's diet.

Larval stage

In the larval stage stoneflies often resemble a mayfly nymph but are generally larger and usually have well defined legs. They also have only two tail filaments compared to the mayfly which has three. The different species range in colour from a light tan through to a dark green. Green and brown are the most common colours however.

Adult stage

On reaching adult hood the stonefly will often climb out of the stream onto surrounding rocks and vegetation. The adult stage is much less important as a food source though can be effective when fishing clear stony streams around Oct to Jan.

 

Imitating the stonefly

Most fly patterns for the stonefly imitate the larval stage as this is when they make up the bulk of the trout's diet.

Stone Fly trout fly patterns include green, black and brown stone flies. The Green Stone Fly is the largest and is best tied in sizes 8 - 12 with others in the 10 - 14 range.