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Entomology

Being a chalk stream the Mimram boasts clean and clear water, an ideal habitat for a whole host of bugs and creepy crawlies. These are of course a vital  food source for the fish and other wildlife. Knowing a little about what lives in and around the water can help the angler greatly. “Matching the hatch” is a vital part of fly fishing and can be the difference between a successful outing and a blank.  Here we’ll go over a few of the more common bugs and aquatic life that are important to the angler.

April will see the first hatches of this Sedge, usually lasting in the region of ten days and they’ll appear from mid morning to late afternoon although mornings would seems to be best. In flight they’ll have a somewhat moth like appearance and on chalk streams are likely to be found in larger numbers in and around weed beds.

Not an aquatic insect but a frequent food source for the trout. These terrestrials will often find themselves blown on to the water and will appear from mid April to the first week of May. They are easily recognized as fairly large black flies with legs that dangle down in flight. The Hawthorn should be found in reasonable numbers around the Mimram due to the suitability of the habitat so look out for these chaps and target the rises where they occur with a suitable fly pattern.

There are 51 species of Mayfly in the UK in varying sizes however the Mimram gets the classic 2-3 weeks of the largest of these flies hatching and seeking mates from mid May to early June. During warm afternoons the nymphs undertake a dangerous journey from the bottom of the river where they’ve spent the last two years to emerge into the air and metamorphosise into the adult stage. Large clouds of males will be seen rising and falling in the sunlight waiting for the females to join them and mate. After mating the females (usually larger and paler than the males) will fly over the water dipping momentarily to lay eggs. Both the nymph and adult stage are major food sources for the fish so replicating them successfully is a must for the angler.

These are the non-biting midges and are present in pretty much all waters and provide a year round food source for the fish. In the larval stage they have worm like segmented bodies and will live in the mud or be free swimming like the Bloodworm. During the pupal stage and the process of hatching they become the most vulnerable to feeding fish where they must hatch and break free of the waters surface tension. They may only be small but trout will often consume huge amounts of these under the right conditions. Hatches can be at any time of year although peaks will be reached from spring to early summer.

The fresh water shrimp isn’t actually a shrimp at all but an amphipod and a good indicator species due to their requirement for a clean, oxygen rich environment in which to live. Luckily for us the Mimram is able to support these in large numbers. They’re complicated little creatures, they have gills and fourteen legs on their thorax and twelve appendages on their abdomen which help with the circulation of water over the gills and swimming. They hatch fully developed from the egg and adults are able to produced two generations in a single year. They’re food for all the fish in the river so some shrimp patterns deserve a place in the Mimram anglers fly box.

This initiative continues to provide interesting information for the club. Sampling has been carried out on five occasions however the majority of this work was completed by just a couple of members and we’d like more help from others so if you’re interested in getting involved please let us know.

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