Barbless Flies

Match The Hatch

The Hawthorn Fly

All the information you need to help get the most from your Hawthorn selection of flies.

The Hawthorn fly (Bibio Marci) is one of the first flies of the season known as 'Terrestrials', these are flies which do not originate from the river, but do end up on it as food for Trout. The Hawthorn Fly is sometimes known around the country as The St. Mark’s Fly, because they emerge around St Mark’s Day (25th April) every year. This fly belongs to the Family Bibionidae and there are around 20 different species found throughout the UK.


Hawthorn flies are found in every part of the British Isles, especially prolific in England, Wales and Ireland. Scotland does have prolific hatches of Heather flies (Bibio pomonae) which are very similar to Hawthorn flies and are discussed below. Hawthorn flies are found around woodland edges, hedges, and wetlands and can be seen in the UK throughout spring.

Hawthorn flies generally start to appear around the 25th April (St Marks day), when they do start to hatch they can be very prolific and you will see clouds of them. They usually only appear in any numbers for a short time and usually into the second week of May, they are gone.

Male Hawthorn flies are around 12mm (size 14 to 12 hook) in length with clear wings, large eyes and long gangly legs (this is the bit we believe the trout home in on - most imitative Hawthorn patterns you see generally extend the length of these rear legs). The females are slightly larger than the males (at around 14mm - a size 12 hook) with slightly smokey-brown coloured wings. You will often see male Hawthorn flies congregating in large swarms flying slowly, up and down, at around head height – trying to attract females.


The Heather Fly (Bibio pomonae) is more prolific in Scotland than the Hawthorn fly, but as far as fly anglers are concerned these species can be lumped together. However, the Heather fly hatches at a different time of year to the Hawthorn Fly, usually from July to September. The Heather fly can be easily identified by its red thighs (see below).

Heather Fly 1200 copy.jpg__PID:07e6371e-7c7e-49c5-aa1b-c5dbedf881aa

Hawthorn - Lifecycle

The Hawthorn Fly has a very short life cycle, hatching and being in flight for only around a week. They start life larva in the soil, this can be for up to 6 months.

During autumn and winter, the Hawthorn fly larvae feed on rotting vegetation. In springtime, the males emerge first followed by the females a few days later. After mating, females lay their eggs in the soil and die soon afterwards and the cycle continues.

Swarms of Hawthorn flies flies may be very annoying when fishing in the early spring, but they are very useful creatures, they feed on nectar, making them important pollinators of fruit trees and crops.

From a fly fishing perspective there is only one stage which we must try to imitate:


Match The Hatch - Hawthorn Imitations

The Hawthorn fly can also be used as a suggestive pattern for a number of different insects, it can imitate a Heather Fly, Daddy Long Legs/Crane Fly and even an adult buzzer. Once the Hawthorn hatch starts on your local river, make sure you have these in your fly box these are also great flies to try when searching stillwaters & reservoirs.

The legs on these flies seem to act as a trigger to the fish. These flies are tied on size 12 and 14 barbless hooks with a bushy hackle, this allows them to create a wake on the surface when retrieved on stillwaters, again another trigger point the fish home into. These flies are also surprisingly effective when fished as a wet fly, so don't be too quick to keep these flies dry, once wet and submerged, if on a stillwater, gently "figure of 8" them back (on a river try fishing them as you would a spider), and hold on!

Top Tip: Fish all these flies in the surface film, do not apply any floatant on them.

Hawthorn Fly

The Hawthorn Fly (or Bibio marci) is a small (no larger than 1cm) black fly, noticeable by its long gangling legs. Hatches of Hawthorn flies usually start in late April and last for no more than a couple of weeks.

This generic Hawthorn fly pattern is tied with long knotted black legs, a back hackle, black hairy body and white wing cases. This fly is available in either size 12 or 14.

Hi-Float Hawthorn Fly

This Hawthorn fly pattern is tied with just a pinch of Deer Hair (for extra buoyancy), long knotted black legs, a back hackle and black body.

This pattern sits really high on the water and is ideal to use in the faster, more turbulant water - apply lots of floatant to the hackle when fishing this pattern in fast water.

CdC Hawthorn Fly

This Hawthorn CdC fly pattern is tied with long knotted black legs, a back hackle, black body and buoyant CdC.

When fishing with this style of fly only apply floatant to the hackle and CdC, as you want the fly to fish in the surface film (not riding high on it like the Hi-Float Hawthorn above).

Hawthorn Suspender

This Hawthorn Suspender fly pattern is tied with long knotted black legs, a back peacock herl collar, black body, buoyant black foam post and a small white wing.

I've always found that this style of 'suspender' pattern is more successful later in the day, when the Hawthorn flies have been blown onto the water and they are starting to sink.

Hawthorn - Hatch Notes

To fly fish a hawthorn hatch, begin by observing the water to identify areas where hawthorn flies are congregating. These insects typically hatch near the banks of slow-moving rivers or still waters, especially during the warmer months.

Use a 3wt or 4wt fly rod, lightweight to handle delicate presentation, paired with a floating line and a leader tapered to between 9ft and 12ft. Select a hawthorn fly pattern that mimics the size and color of the natural insects.

Approach the water cautiously to avoid spooking the fish and make gentle casts near overhanging branches or vegetation where hawthorns may fall, or be blown, onto the water. Allow the fly to drift naturally with the current, periodically imparting subtle movements to mimic the struggling motion of a real insect - do this by either moving the rod tip or making slight pulls on the fly line.

Be patient and observant, as trout often take hawthorn flies with subtle rises or delicate sips. Keep a keen eye on any signs of feeding activity and adjust your presentation accordingly to entice strikes from eager fish.