Feeding trout flies to match the hatch

by Rob Heal | May 10, 2021
Angler sits in a boat with an opened case of trout flies to select from.

Trout fly selection can be a challenge, particularly during times when insects are less active. Some anglers will overthink, while others will underthink.

Having a starting point, rather than just tossing something out, will put you on the path to greater success.

Time of year

You should have a general idea of what insects should be hatching on the river you intend on fishing for that time of year. Some mayflies and caddis will be active for several months of the summer, while some species will only be on the river for several days to a week. Online hatch charts are a good information source, so is asking for hatch updates at a local fly shop.

Apr.-May Focus on small- (#18) and medium-sized (#14) mayflies, like an Adams pattern

May-June Mayflies are generally larger (#8-12), tan caddis (#14-18), and crane flies (#16-18)

June-Jul. Mayflies are mixed, darker (#12) and lighter (#16-20), tan or dark caddis (#14-18), and crane flies (#16-18)

Jul.-Sept. Mayflies generally smaller and lighter (#16-20), tan caddis (#14-18), and crane flies (#16-18), terrestrials, like ants, grasshoppers, crickets, come into play

Go to flies

Here are my 12 favourite flies that, tied in different sizes and colours, will serve you well for most fly hatch situations in Ontario.

A typical day

Seldom does everything go right on a fishing trip. Conditions will vary and you will have to work harder to find trout and what they are eating. Here’s how I work through it:

  • Let’s say that you were informed by the local shop to expect a good caddis hatch in the morning, with sporadic hatches throughout the day. In the evening, you were told to anticipate a light Cahill mayfly emergence that will then fold into a spinner fall near dusk. You can also expect midges and crane flies, particularly in the morning. Use this knowledge as a starting point.
  • You arrive at the river at daybreak, expecting to see trout rising to caddis as the shop told you. But nothing in trout fishing is consistent; what happened three days ago, or even yesterday, might not occur today. However, you know trout have at least been experiencing caddis and it’s a good bet that they are used to seeing them. Begin casting a proven caddis pupa or emerger such as the LaFontaine Sparkle Pupa or an Iris Caddis, fishing just under the surface. Basically, what you are doing here is playing the odds and showing the fish what they are used to seeing.
  • If you haven’t hooked anything, don’t start making a drastic change. My next move would be to add one or two size 6 split shot to the leader to get the fly drifting deeper in the column and hopefully in front of feeding fish.

    While trout might appear uncooperative, it doesn’t mean that they are not feeding. A condition-related factor, like a drastic drop in the barometer or water temperature, may have slowed the fish. Adjusting the depth of your fly may yield success .

Be aware of what is going on around you. You might spot a second insect, perhaps midges, coming off while you’ve been presenting caddis. If insects are in the air, their larvae are in the river.

  • If going deeper fails, I will consider a fly change but staying within the caddis line. I might shift to a larva, such as the venerable, green caddis larva in the relevant size but keep it deep.
  • My next move would be to downsize my tippet to a small chironomid, such as an 18 or even 20 brassie. I will continue to change flies, but keep them within that core group that I know to be most active.
  • I wouldn’t be out of the norm to hook the odd fish during the trial-and-error process. However, that doesn’t mean that you’ve sorted it all out. So how long do you stay with a fly? That depends on many things, but as a rule of thumb, I search the entire piece of water that I am focused on with each fly, making sure to cover as much water as I can and show my fly to as many fish as possible.
  • If I start seeing mayflies hatching, I will tie on a mayfly nymph, such as a pheasant tail. This is one pattern that will nicely cover most of the major mayfly nymphs and keep you in the game. If I start to see fish at the surface, a Usual or an Adams comparadun will serve well, as will an emerging mayfly or the dun.
  • Sometimes, despite our best efforts, the going can be tough. During these periods, don’t be afraid to go against the grain. A San Juan worm or a hellgrammite, to name a couple, may just persuade a complacent trout to eat.

Originally published in the May 2020 issue of Ontario OUT of DOORS.

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