Winter Bug Guide

All the key insects you need for winter

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Most of us anglers dread colder weather.  It’s the end of the season and life without fly fishing for the next six months is overbearing and depressing. The silence in the winter months is reflective of the insect activity.  Most insects are dormant, birds are layed up in the trees puffed up to survive the cold weather and the lack of movement shown both in the wildlife and the pace of the river makes for a tranquil environment.  This is winter fly fishing.  To enjoy winter fly fishing takes equal measure of passion and insanity to brave the cold weather, freezing hands and guides for the hopes of a few fish.  Once you experience a good day of winter fly fishing however, something about the onset of colder weather peaks your interest.

Low crowds, tranquil waters and chances to catch large trout are some of the most appealing aspects of winter fly fishing.  In order to catch fish during the winter, you need three things:

Proper Fly Selection | Effective Presentations | Productive Locations

If you can get enough of those three, you’ll find fish.  

In this article, we’re going to provide you with a guide to winter insects and food sources for trout.  We’re not saying you can’t throw a hopper in winter and find a fish or two that will attack it, but we are saying that if you want to have repeated success on the river, learning these insects and stocking them in your box as fly patterns will land you more fish.

List of Winter Insects for Fly Fishing

Insects and Food Sources for Frigid Temps

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The best news for winter fly fishermen is that there are less options to work through in winter months.  Fish are really only going to eat 7 out of the 12 major food categories.  To be more exact, you’ll probably only find fish feeding on 2-4 of these on any given day, and as you work through your flies, you’ll be able to quickly find the right flies.

Let’s go over each insect category below, the stages you should focus on and the sizes and colors.  We’ve included hatches as well for any insect that has an active hatch during the winter months which is Mid October to Mid April depending on where you live:


midge adults

Midges will be the bread and butter of the winter fly fishing , and make up the majority of a trout’s diet.  Midges will hatch during the warmest parts of the day often from 10 – 3 pm and can bring nearly every fish in the river to the surface.  This hatch alone can make winter fly fishing worth pursuing.

  • Stages: Nymph, Emergers, Dries
  • Sizes:  #18 – #26
  • Colors: Black, Blue, White, Red, Purple, Olive, Brown
  • Hatch Times: 10 -3 pm warmest part of the day


bwo-male-mayfly-dryMayflies during winter primarily consist of Blue Wing Olives aka Baetis (BWO).  These mayflies hatch when the water temps get above 38 degrees and are best between 40 – 44 F.  They will also hatch during the warmest parts of the day 10 – 3 pm and can hatch on sunny days, cloudy days, windy days and snowy days.  Water temps and barometric pressure are the most important to predict a hatch.  Fish changes in weather with warm water temps and you’ll have the best chance for BWO hatches.

  • Species:  Only BWO (aka Baetis, Blue Wing Olives)
  • Stages: Nymph, Emergers, Dries
  • Sizes: #18 – #24
  • Nymph/Emerger Colors: Black, Purple, Olive, Dark Olive
  • Dry Colors: Olive, Dark Olive, Purple
  • Hatch Times: 10am – 3pm – Warmest Part of Day


stonefly-bwMost stoneflies have up to a three year lifecycle and are always present in the water system.  I love fishing a stonefly nymph in a two or three fly nymph rig and using the inherent weight of a larger fly to get my smaller nymphs down in the strike zone.  It’s hit or miss with stoneflies in winter, but they can catch fish any day of the year and are worth a spot on your rig.

  • Stages: Nymph
  • Sizes: #8 – #16
  • Colors: Mixed or Solid Colors of Black, Brown, Yellow


Case-building caddisfly larva (Trichoptera)Caddis are really only present as nymphs during the winter months and their larva patterns are either cased or free form.  The free forms look like monstrous midges and the cased caddis have cases built out of river material around them like a cross between a hermit crab and a butterfly.  Fishing deep to the bottom of the river with caddis nymphs will pull some fish during the winter and is a good bet if the above isn’t working.

  • Stages: Nymph
  • Sizes: #10 – 18
  • Colors: Brown, Olive, Dark Olive, Black, Cream

Scuds & Sowbugs

Scud_Gammaridae-960x637 (1)Scuds and sowbugs are present in spring creeks and tailwaters with ample vegetation.  Fishing these as a lead fly during winter is a good option if you’re fishing the aforementioned river types.  The further scuds get down from the tailwater outflow, the more brightly colored they become.  As they die, they become brightly colored or as they ingest parasites, both of which happens the longer they are alive.  Fish hot spot patterns and regular patterns until you find the option that works best for the day.

  • Stages: Nymph
  • Sizes: #12 – #18
  • Colors: Tan, Olive, Pink, Orange with Hotspots of Red (optional)


Sludge_worm_Tubificidae-960x637Annelids, aka aquatic worms are active year round in the water system.  Usually as flows rise, the annelids get flushed downstream and fish will target them more.  Regardless, the trusty san juan worm or a squirmy worm can be some of the most dependable bugs during winter.  

  • Stages: Nymph
  • Sizes: #8 – #16
  • Colors: Red, Pink, Tan, Neon Green

Egg Patterns

trout-eggsEggs exist from the brown trout spawn and provide an easy and nutritious meal for trout all winter. As flows increase, and the eggs get dislodged, they becomes more prevalent.  Big changes in flows makes a good day for the classic “bacon and eggs” rig.  Eggs are often brightly colored and serve as an attractor, motivating the fish to move for your bugs.  Often you’ll get a fish to move to an egg and end up eating the small midge you have trailed below it.

  • Stages: Nymph
  • Sizes: #10 – #14
  • Colors: Mixed or Solid Colors of Red, Orange, Pink, Yellow, White


Winter fly fishing can be an amazing experience, but learning your insects is an important part to the success. Use this as a guide to help you plan your winter fly box.

Winter Fly Assortment

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