Large Dark Olive
Kite's Imperial
Dry fly · #14-16
On the surface
For fish taking large dark olive off the top.
What to tie on
Fly selection by river and month
Most fly boxes are a museum of everything their owner has ever bought. A box that fishes is much smaller than that, and it is chosen for the water and the week rather than collected. Tell us where and when you are going and we will build one from that river’s hatch calendar.
The sets cover the surface, the film and the bottom instead of handing you five versions of the same olive. Every fly comes with the hook size to ask for, the hatch it is there to match, and where to buy it when we have found a confirmed match.
22
rivers covered
397
hatch records
17
fly patterns
8 flies for the River Test in October
Daddy Long Legs
Terrestrial · #10-12
Blown inDaddy Long Legs get blown onto the water on a breezy day.
- Freshwater Shrimp
Sawyer's Killer Bug
Nymph · #12-16
Under the surfacesubsurfaceFor when nothing is showing. Freshwater Shrimp are there regardless.
Caperer
Sedge · #10-12
Evening sedgeCaperer come off late; this covers the last hour.
Check the beat rules before you fish. Chalk stream beats set their own, and they vary. Plenty are dry fly only. Others allow a nymph but not before a set date, often 1 July, and a few bar it all season. The flies marked above are the ones that would be affected.
Nothing in this water’s calendar covers in the film in October, so the set leaves that out rather than guessing.
We get a small commission if you buy through these links, and it costs you nothing extra. If the calendar has been useful and you feel like supporting an independent site, buying your flies this way is an easy way to do it.
How the set is put together
The obvious way to build a fly list is to take the heaviest hatches for the month and stop. That gives you five olives and nothing to fish the moment the rise stops, which on a bright afternoon is most of the day. So the generator fills roles instead, and each fly in the set is there to answer a different situation.
On the surface
Two dries matching the month’s main upwings, for a fish that is already looking up. This is the fishing people come to a chalk stream for.
In the film
An emerger for the fish that rises at everything and takes none of it. Nine times out of ten it is taking them just under the surface, not on it.
Evening sedge
Caddis come off late. The last hour can be the best of the day, and the rise often runs on until you genuinely cannot see the fly.
Blown in
A terrestrial for a breezy day, when hawthorns, black gnats or crane flies end up on the water by accident rather than by hatching.
Under the surface
A nymph for when nothing is showing, which is most of the time. Fished upstream to a visible fish, this is the other half of chalk stream fishing.
Searching
A shrimp pattern. Freshwater shrimp are the commonest thing a chalk stream trout eats and about the only one it actively hunts along the gravel.
If a river’s calendar has nothing for a role in that month, the set says so and leaves it out. We would rather hand you six flies that are right than pad it to ten.
What the flies actually are
Almost everything a chalk stream trout eats belongs to one of four groups, and once you can tell them apart the fly box stops being a lucky dip. Upwings are the mayflies and olives, the classic chalk stream insects. They hatch out of the water, sit on the surface to dry their wings, and that pause is what makes them worth imitating. A dry fly is the dun, the freshly hatched adult. A spinner is the same insect after mating, dying flat in the surface film with its wings out, which the fish often prefer because it cannot get away.
Sedges, or caddis, are moth-like and mostly an evening affair. They skitter rather than sit, which is why a sedge pattern can be twitched where an olive should be left alone. Midges and their pupae, which anglers call buzzers, are on the water every month of the year and are badly under-used on rivers. And terrestrials are the land insects that arrive by accident: hawthorn flies in late spring, black gnats all summer, crane flies through the autumn. They only matter when the wind is right, and then they matter a great deal.
Underneath all of it sit the nymphs and the freshwater shrimp. The shrimp are not a hatch at all, they are simply always there, in numbers, and a trout will work a gravel run picking them out when there is nothing in the air whatsoever. If you only carried one subsurface fly on a chalk stream, a weighted shrimp or a Pheasant Tail would be it.
Size matters more than pattern
The single most common mistake on clear water is fishing a fly that is too big. Chalk streams are shallow, slow and bright, the fish get a long look, and a size 14 where a 16 was needed will be refused all afternoon by fish that would have taken the same pattern two sizes down. Carrying one fly in three sizes beats carrying three flies in one size, and it is a cheaper box.
Sizes also drift through the season. Spring olives are big enough for a 14. By August the same family of insects is coming off at 18 or smaller, and the caenis of high summer will have you squinting at a 20. Hook sizes run backwards, so a bigger number is a smaller fly. The sets above give the range each pattern is usually tied in; if you are between two, take the smaller one.
How the fly sits in the water matters just as much. The same olive tied as a high-riding dun, a parachute and a flush emerger will fish as three different flies, and the fish will often want exactly one of them. That is why the set includes something in the film rather than three variations on the surface.
The chalk stream year
Chalk streams run clear and cold all year because they come out of the ground rather than off the hills. That is why the hatches are so much more predictable than on a rain-fed river, and why a calendar like this is worth anything at all. Midges and freshwater shrimp are there every month. Everything below is what changes.
January
Nothing seasonal recorded. Grayling fishing on midges and shrimp.
February
Nothing seasonal recorded. Grayling fishing on midges and shrimp.
March
Large Dark Olive
April
Grannom, Hawthorn Fly, Large Dark Olive, Black Gnat
May
Hawthorn Fly, Sedges, Mayfly, Black Gnat
June
Blue Winged Olive, Sedges, Mayfly, Black Gnat
July
Blue Winged Olive, Sedges, Black Gnat, Caenis
August
Blue Winged Olive, Sedges, Black Gnat, Caenis
September
Blue Winged Olive, Large Dark Olive, Sedges, Black Gnat
October
Blue Winged Olive, Large Dark Olive, Sedges, Caperer
November
Large Dark Olive
December
Nothing seasonal recorded. Grayling fishing on midges and shrimp.
Built from the hatch records for all 22 rivers, ranked by how heavy each hatch is and how many waters carry it. Individual rivers differ, sometimes a lot, so use the picker above for the water you are actually fishing.
Rivers covered
We hold hatch calendars for these 22 rivers. Each has a full year of hatches on its river page, alongside the beats you can actually fish.
FAQ
Fly selection FAQs
What to put in the box, when the hatches actually happen, and how far to trust a calendar against the weather on the day.
01 What flies should I take to a chalk stream?
Cover the water rather than the hatch. A box that fishes a whole day needs something on the surface for a rising fish, something in the film for one that keeps refusing the dun, a nymph or two for when nothing is showing, and a shrimp pattern for searching. Six to eight flies chosen that way will out-fish thirty of the same olive in different sizes. That is how the generator on this page assembles a set.
02 When is the mayfly hatch on English chalk streams?
The bulk of it runs from about the middle of May into the first half of June, which anglers still call duffers fortnight. It is the heaviest hatch of the year and the easiest dry-fly fishing, and beats price those weeks accordingly. Timing moves with the spring: a cold April pushes it later, a warm one brings it forward. It is also not uniform. The Test and the Hampshire Avon get a far heavier hatch than the Itchen, and Driffield Beck in Yorkshire has no mayfly worth the name.
03 What can I fish in winter?
The trout season is closed over the winter on most English chalk streams and the fishing is for grayling. That narrows the box considerably: midges and a weighted shrimp or bug account for most winter fish, with a small dark olive on the milder days. The generator reflects that and will hand you two or three flies for December rather than pretending there is a summer box to sell you.
04 Are these live hatch reports?
No. They are the months a hatch usually runs on that water, taken from published hatch charts and our own records. Weather moves all of it. A cold north-easterly will shut down a hatch the calendar says is at its peak, and a warm spell will bring one on a fortnight early. Treat the set as what to pack, not as what is happening today, and ask the keeper when you book.
05 How many flies do I actually need?
Fewer than most boxes contain. The sets here run to six or eight patterns because that is what covers a day on a chalk stream. What matters more than the count is size and how the fly sits in the water. The same pattern in a 14 and an 18 will solve more problems than two more patterns in one size.
06 Why do some flies have no price?
We match patterns against the Sportfish and Farlows catalogues and a confirmed match is not always there, either because the pattern is not stocked or because the name they sell it under is different enough that we would rather show nothing than send you to the wrong fly. Those patterns still appear in the set, because the set is fishing advice first.
Where this comes from. The hatch records are drawn from published chalk stream hatch charts and standard UK entomology, checked against more than one source. The patterns are the standard UK dressings, and prices come from the Sportfish and Farlows catalogues.
These are typical months, not a live report. A cold spring or a hot dry week will move any of it, and a fortnight either side of a hatch window is normal. The keeper will always know better than a calendar.
