HOOK: Size 10 – 16 wet fly.
THREAD: Black 8/0.
BODY: Three sections of dubbed seal’s fur – black, red, black.
RIB: Oval silver tinsel (wire in the smaller sizes.)
BODY HACKLE: Black cock, palmered.
SHOULDER HACKLE: Black cock, slightly longer than body hackle.

This is a good general pattern which can be fished wet or dry. The Bibio was originally invented to imitate the heather fly or ‘bloody doctor’. This is a close relative of the hawthorn fly which usually appears in upland areas during August. The natural insect has red or orange legs which are suggested by the red in the dubbing. In spite of this, the Bibio is particularly effective when there are black gnats or hawthorn flies about. These terrestrials can appear in large numbers during late April and early May and when blown onto the water, they can cause a good rise of trout. The hatches are very weather dependent, a cold wet spring means they may hardly appear at all. Cool weather may restrict them to the bankside undergrowth and they will be unlikely to fly and so not get onto the water. A warm, sunny, and breezy spring day can result in some of the best fishing of the year.
I would usually fish two of these on a fluorocarbon leader, 10 and 12 for a fall of hawthorns or 16 and 14 for a fall of black gnats. The flies are oiled to float and left static while the leader sinks. If a fish doesn’t take them from the surface, a long steady draw on the line should sink the flies which are then retrieved sub-surface with a ‘figure of eight’ retrieve. If you tie your own flies, there is a useful variant of the Bibio which was shown to me by one of my fishing chums. Instead of the three part body, the dubbing is made up of a 50-50 mix of black and orange seal’s fur. It is another excellent fly but I don’t think it was ever given a name. Here it is below:

Other flies to watch out for during May are the usual midges and beetles, plus alder flies and the first hatches of Sedges towards the end of the month. There may also be Aphids and Dung flies falling onto the water.
Now the warmer weather has arrived, fish will be at or near the surface most days and flies fished in this zone will have a good chance of catching.
Phil Bilbrough