Harbingers of spring

the four flies you need to be aware of for spring success

The opening of the trout season in March in some parts of the country is, in truth, more of an acknowledgement of impending spring than an invitation to fish, writes Peter Lapsley. Trips to the river so early in the season have more to do with hope than expectation. Two things need to happen before that can change. The trout have to recover fully from spawning and the rigours of the winter, and the water temperature has to rise to a level at which both they and the insects they feed on begin to stir themselves. Nowhere in Britain do those things usually happen until mid-April, a magical month in which we may at last head for the river with reasonable optimism.

Identifying the flies that appear in April is not difficult. There are really only four species that are widespread and of consistent interest to trout and anglers alike, and identification is simplified even further by the fact that there are few areas in which all four occur. 

The first is the March brown (Rhithrogena germanica), a creature of fast-flowing, stony, rain-fed rivers, which largely confines its British distribution to Scotland, Wales, and the North and West of England. 

American readers may wish to distinguish our March brown, also, from their ‘Western March brown’ (Rhithrogena morrisoni), which, in central and North Eastern states, appears at about the same time as Rhithrogena germanica. Although the female is much lighter in colour than her European counterpart, the male is similar in both size and colour. So, while I have never tried it, it seems not unreasonable to suppose that a British artificial might be as effective in the US as it is here.

The second early season fly that can bring trout to the surface and joy to anglers’ hearts in April is the large dark olive (Baëtis rhodani). Widespread and abundant throughout the British Isles, it compensates fly fishers in the Midlands and the South of England for the absence of the March brown from their waters.

Confident identification of the large dark olive is quite simple because, apart perhaps from the March brown, it is almost always the only fly on the water during the first half of April, and the two species differ substantially in size and wing colour. The large dark olive is only about three quarters of the size of the March brown, the body of which is about 12mm long. And, more readily noticeable are the large dark olive’s pale grey wings which contrast sharply with the mottled brown wings of the March brown.

It is often said that trout are more inclined to take large dark olive nymphs or emergers than winged adults. Maybe. It is certainly true that trout take the artificial nymphs and emergers very enthusiastically. But having experienced countless large dark olive hatches, during which I have had great sport with high-floating Kite’s Imperials and John Goddard’s Super Grizzlies, which I now prefer, I would be wary of being too adamant about it.

The third fly seen on many rivers in central Southern and South West England, in Wales and Yorkshire, on the Ribble and the Eden, and in parts of Scotland, is a caddis fly, the grannom, (Brachycentrus subnubilis). It can be frustratingly localised, not just to individual rivers but to particular stretches of those rivers. Where it does occur, the hatches may last for anything from a few days to a couple of weeks, running from mid-morning to mid-afternoon.

Back in the early 1980s, I was fortunate to have a rod for four years on two and a half miles of the lovely little river Ebble, to the south of Salisbury, between Coombe Bissett and Odstock – unstocked, very lightly fished and with a wonderful head of wild brown trout to about a pound, or sometimes a tad more.

Courtney Williams in his Dictionary of Trout Flies said that, during a hatch, the fish were often as enthusiastic about the pupa as about the adult. He evidenced some confusion about the difference between the larva, a creature which creates a case for itself which it drags around on the stream bed and amongst the weeds; and the pupa, small, free-swimming and entirely different from the larva in both appearance and behaviour. And he offered only one pattern, GEM Skues’s somewhat questionable dressing for the ‘Grannom Nymph’, whatever that may be. With a body of bright green tapered wool and a rich brown partridge hackle, it sounded to me like an indifferent attempt to represent the larva, rather than the pupa.

The fourth fly in the catalogue of ‘harbingers of spring’ is the hawthorn (Bibio marci), so-called because the female usually puts in her first appearance around April 25, St Mark’s day. The males, which are smaller than the females, sometimes show up a few days earlier. The hawthorn seems to be very much a ‘morning fly’, busily in evidence until midday or very early in the afternoon and then disappearing completely. Its hatch usually continues until the end of the first week in May, when it ceases quite suddenly. 

Hawthorn flies are terrestrials, their larva feeding on the roots of grasses and on decaying vegetable matter. They are therefore unaffected by the general malaise – the combination of siltation and diffuse pollution – that has so depleted aquatic invertebrate populations in so many British rivers over the past 20 or 30 years. Indeed, my own impression is that hawthorn hatches have been becoming increasingly prolific, but that is not to say that they necessarily offer certainty of success.

By the time the hawthorn hatch is over, a raft of other flies are beginning to put in their appearances – medium olives and small spurwings; then, if we are lucky, iron blue duns; and there are only a couple of weeks to go to the beginning of the Mayfly, but that’s another story.