Note: strictly the genus name is Baëtis, but as people searching for information on the internet do not generally include accents (diacritical marks) such as the umlaut above the character ë, we have used the easier-to-type Baetis in the main text of this page.
In the early days of flyfishing, the name Pale Watery was applied also to several other pale up-winged flies including the Small Spurwing, Large Spurwing, and Pale Evening Dun. In Britain and Ireland today the term Pale Watery is reserved specifically for Baetis fuscatus, a fly that in its dun stage in particular does indeed have a pallid, almost ghost-like appearance. (Okay, so not everyone may have had the necessary experience be able to compare this fly with the last ghost they saw!)
Pale Watery nymphs are agile darters with slim, torpedo-shaped bodies. From an angling point of view they can all be grouped together, as there are no distinguishing features that could possibly be detected even by the most discerning of trout or grayling. The nymph in the picture above is an Iron Blue, Alainites muticus, but the only easily-spotted differences between this and a Pale Watery nymph is that the latter has a middle tail only slightly shorter than the other two and there are dark bands midway along the otherwise pale tails - those bands are not present on an Iron Blue nymph. Incidentally, they are present on the tails of the Small Dark Olive nymph; this makes differentiating between Small Dark Olive and Pale Watery at the nymph stage very difficult indeed without resorting to the use of a microscope.
A size 16 Pheasant-tail Nymph is a good match for the Pale Watery Nymph, while a Gold-ribbed Hare's Ear (GRHE) matches the emerger stage.
The medium olive is an important summer fly on chalkstreams and on many spate rivers too. Peak hatches occur in May and June, but these flies are to be found on rivers in Britain and Ireland through until at least August.
The dun hatches from mid morning until late afternoon or early evening and tends to come off the water in a trickle hatch (unlike, for example, March Browns, which usually come off in flushes). A nymph will swim up ton the surface and then it splits open its exoskeleton above the thorax - the central part of it body to which the legs and wings are attached; the thorax is the part between the head and the abdomen . Out of the exoskeletal shuck crawls the dun, its wings crumpled up like a folded parachute. The wing veins fill with fluid, which takes at least a few seconds, depending on the temperature, and then the wings stand up straight and are strong enough to allow the dun to take its first faltering flight to the safety of bank-side bushes.
The male Pale Watery dun is distinguished from other small pale upwinged duns by its large yellow-orange eyes (the eyes of male duns of Baetis scambus, the Small dark Olive, and Baetis vernus, the Medium Olive, are brown).
Trout show no tendency towards gender prejudice as far as Pale Wateries are concerned: they seem to be equally pleased to meet Mr or Mrs Baetis fuscatus!
Pale Watery duns are most commonly seen emerging in moderately shallow, medium to fast stretches of rivers, where River Water-crowfoot beds (Ranunculus fluitans, for example) provide the nymphs with cover from predators and plenty of algal-coated leaves to browse upon.
Many of the duns emerge where the beds of streamer weed are so dense that trout either can't see them or can't get to them even when they can see these potential snacks escaping.
On gentle chalkstreams and lowland limestone rivers, where the water in summer is as clear as gin and trout have plenty of time to inspect surface flies as they drift lazily along, a traditional hackle fly is not always good enough.
One innovative solution, devised by chalkstream expert Neil Patterson, is to alter the tying style so that seen from underneath the artificial fly has two rows of legs with a clear gap in between rather than a tangles mass of hackle points. (Trout can't count, so having a few more than six legs is not a major problem.)
The Funneldun technique can be applied to advantage to any hackled dry fly pattern, and it's not a difficult form of fly to tie..
In Matching the Hatch I explain how the forward-sloping hackle and humpy thorax can be tied to make a very good representation of the Pale Watery dun or of other similarly pallid up-winged river flies of summer.
On warm summer evenings, from sunset until dusk, the female Pale Watery spinners return to the water to lay their eggs, but unlike many other up-winged flies they do this in a way that greatly reduces the chance of them being eaten before this final task, crucial to the survival of the species, has been completed.
The spinner alights on a partly-submerged rock, tree branch, reed, bridge piling etc and, having folded back its wings, crawls down beneath the surface. There, on a rock or weed she deposits her eggs next to one another in a compact group.
The main opportunity for trout to take Pale Watery spinners from the surface of the water is as the females return to the surface after laying their eggs. In most cases they will be swept away on the current, there to die and become a spent spinner. An artificial spent spinner pattern seems a wise choice, therefore.
Males get blown onto the water on breezy evenings, and occasionally the result is a selective evening rise. The male spinners are distinguished by their very pale bodies and large yellow eyes. Like the spinners of the Iron Blue, their abdomens are translucent white with just the final three segments coloured orange-brown.
With weed growth at its most dense in summer, chalkstreams and other plant-rich rivers are characterised by complex patterns of surface turbulence, especially in low-water conditions.
Making a spent spinner imitation drift without drag is very difficult in these conditions, and it is made much harder when you have to use a small fly that has very little contact with the water surface.
Brian Clark's solution to this, which I now use extensively because it is better than any answer I devised for myself, is to make spent wings out of kitchen bag polythene. The Poly-winged Spinner has an orange-brown body but no hackles, and so it lies flat in the surface film with maximum surface contact - just like the real thing!
Of course, it's still possible for your artificial fly to suffer drag, but there are things you can do to minimise it. One of the most valuable techniques I know is the 'wiggle cast'. To make your leader land in drag-absorbing 'snake', make a cast and, while the line is still shooting through the rod rings, gently waggle the rod tip from side to side. It looks impressive when an expert makes a wiggle cast, but actually it is a surprisingly easy technique to master. Try it!