This article will hopefully  introduce you to the main types of fly that you will see by the river and which trout are interested in feeding on.

They are divided into four main catergories:

· Up winged (Ephemeroptera)  May fly

· Roof Winged (Trichoptera)    Sedge fly

· Flat Winged (Diptera)             Midge

· Hard Winged (Plecoptera)      Stonefly   

I will attempt to explain each group in turn.
 
Up winged:
 
All these flies have a segmented body, two or three long tails and two large upright transparent or opaque wings. Almost all also have two additional smaller hind wings.
 
The life cycle of the classification normally has four stages as follows:
 
Eggs: Deposited in the water surface or below water surface against weed growth and subsequently sink to the bottom and attach themselves to stones or weed. This stage can last between days and even up to several months.
 
Nymph: Following hatching a larval or nymph forms. During this stage the nymph remains close to or hidden around stones or weed on the bottom of the water. It develops into a larger nymph periodically during it life by shedding or moulting its outer skeleton.
The majority of nymphs feed on decaying vegetable matter. This stage can last for a short period up to two years.
 
Dun or sub-imago: When the nymph is fully grown it then becomes ready to emerge from the nymphal case and become the up winged dun seen during a hatch of fly. This takes place relatively quickly when the nymph rises to the surface of the water and splits normally on its back. The metamorphosed fly then crawls out, pumps the wings full of blood and then flies.
The fly remains in this form from between 12 and 36 hours depending on conditions.
There are flies that transform from nymph to dun and then to spinner within minutes.
 
Spinner or imago: This is the final stage of the life cycle where the fly again metamorphoses into a sexually mature fly and mates in the air. The females return to the water and deposit the eggs so restarting the cycle. This stage often only lasts a matter of hours.
 
   
 

Roofed winged flies:

This group of flies includes over 190 different species of sedge or caddis fly. They are different in that they have a v-shaped roofed wing when at rest. They have four distinct stages in their life cycle.
 
 
 
 
Egg:  

The female sedge can deposit her eggs into the water by three specific ways:
· On the water surface.
· By crawling underwater and depositing the eggs.
· On vegetation or herbage overhanging the water.
The eggs hatch within 10 to 12 days into the caddis larva.
 
 
   
Caddis Larvae:

Most caddis on hatching building themselves a protective case by spinning together small stones or vegetation. This is not true of all species of sedge and they are described as caddis worms. Within days or weeks depending on the conditions the larvae will be fully grown and stop feeding. At this stage they will pupate.
 
 
 
Pupa:

The pupa forms and develops strong paddle like legs which it will push its way from the water bed up to the surface. At reaching the surface the case will split and the fully mature adult will emerge onto the surface. Some do so with a lot of movement and skitter about frantically.
The adult can survive longer periods that mayflies and only mate at rest with only the females retuning to the water to egg lay.

 

Flat winged:

This is probably the largest group of all flies and includes the common house fly, mosquitoes, dung flies and crane flies. The species of interest to anglers are the reed smuts, midges and gnats.

Only a few of these flies are aquatic.
 
Eggs:

Laid onto the water or onto vegetation.
Eggs hatch into larva.
 
Larva:

The larva normally stays in mud and are commonly called bloodworm because of their deep blood red colour. The larva feeds and develops into a pupa:
 
Pupa:

 When ready to emerge the pupa ascends to the surface and the adult breaks through the pupal sack into the air and flies away. They then mate and die. All flies in this category are tailless and have two short flat transparent wings.
 
 

 
 
Hard winged:

This group are commonly known as  stoneflies. They only have three stages of development.
 
Egg:

The eggs are laid by mature insects on the water surface. These hatch into a nymphal stage.
 
Nymph:

The nymph that develops are different from others in that they have only two tails and also have two antenna. They are robust and active hunters and can be over an inch long. The nymph grows until ready to transform into the adult fly. It crawls out of the water onto either vegetation or stones and the adult emerges from the back of the nymphal sack.
Stonefly: The adult can be recognised by the fact that it has four wings. They are normally poor fliers and when not flying the wings fold away flat across its back. 

 
   
Other Classifications
 
 
This list defines other classes of insect ha are relevant to fly fishing for trout.