Sunday Classic / The Moth Larva Hatch

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Klewein’s Giant Oak Leaf Caterpillar. Photo By: Louis Cahill

Previously published in last issues Southern Culture On The Fly Magazine.

As I relived last year’s spring fishing season in my head searching for the perfect hatch, the color of bright green began entering my conscience, and bam! Like a slap to the face, it hit me.

Every year we get a month-long trout feeding frenzy, as moth larva burst onto the scene by the tens of thousands. Yes, I’m talking about the green weenie, the inch worm. The tree limb-repelling caterpillars that every trout in the stream will gorge themselves on through the month of May, and well into summer. Multiple species of moth larva ranging from 1-2″ long annually coordinate a synchronized blanket hatch during late spring that ends up packing the bellies of trout with protein-rich, green gummy goodness. Anglers smart enough to take advantage of this late spring phenomenon can find themselves fooling the biggest trout in their waters.

Timing the Moth Larva Hatch

For the hottest and most consistent fishing, the best time by far to target the moth larva hatch is during it’s early stages. The blanket hatch usually begins the first week of May in North Georgia, but can start a little later depending on how far north you live in the Southeast. Because this hatch unfolds and gains momentum so quickly, it takes very little time for trout to recognize the new food source and begin keying in on it. As soon as I spot the first moth larva of the year, I begin working the larva imitations into my fishing within days. This way I can monitor their effectiveness, and do a much better job of timing the hatch during its peak periods. When most of the trees have gotten the new years foliage, you should start anticipating the hatch to begin.

Fishing the Moth Larva Hatch

There’s basically three ways you can go about fishing the moth larva. The best technique and rig depends on the size and depth of water you’re fishing. It’s also very important to pay attention to how the fish are feeding on the hatch (surface or subsurface), and where you’re locating the concentrations of trout. Here are the two main rigs I use when I’m zeroing in on the moth larva hatch:

Rig 1. Buoyant Dry Fly with Inch-worm Dropper

You can fish a floating inch worm pattern solo like a dry fly. Most of these patterns are tied out of deer hair or foam. They float well, but it can be hard to find the correct shade of tying materials to match the color of the naturals. Because of this, I generally opt for dropping a simple, bright green ultra-chenille inch worm pattern 18-20″ off the back of a buoyant dry fly. You can tie them up in a third of the time of the deer hair patterns, and if you add floating, it floats well enough.

This rig works really well on small streams where most of the water you’ll encounter will be moderately shallow. It also will allow you to present your larva patterns under foliage located along the banks much easier, where hungry brown trout often position themselves during the terrestrial season. They dry dropper rig is a great choice when you’re constantly targeting shallow water hot spots and want to limit hang-ups on the bottom.

Rig 2. Deep Water Moth Larva Nymph Rig

My favorite way to fish the moth larva hatch is to nymph them under a strike indicator. Everyone seems to assume that moth larva spend most of their time floating on the surface. Although the small guys (inch worms) you see hanging from a silk thread do float naturally, other species like the oak leaf caterpillar (Lochmaeus Manteo) that are much larger, sink like a rock. Buying into fishing caterpillar patterns on or near the surface was a big mistake I made early on fishing the moth larva hatch. I though the majority of the trout were taking them on the surface , when in reality, I bet that 75 percent or more of the naturals are begin eaten by trout subsurface as they tumble along the stream bottom. Moreover, its’s also important to note that even the floating inch worms will eventually get sucked under the surface as they drift through turbulent water downstream. Day in and day out during this prolific hatch, I have the most success fishing moth larva imitations deep on a nymph rig. Sometimes I’ll fish a big oak leaf caterpillar with a smaller inch worm version off the back. But most of the time, I’ll pair the moth larva up with a smaller natural colored nymph dropper.

Types of Water

I’ve found that targeting and fishing the moth larva hatch is most productive on small to mid-size streams where good overhead tree canopies are the norm. However, don’t fool yourself into thinking the hatch is unimportant on your big rivers. I’ve had equal success on freestone rivers and tailgaters fishing moth larva patterns. Here’s the key difference: instead of targeting all the water on the big rivers like I do on small streams, I only concentrate on sections of water where the banks have heavy foliage and there’s overhanging trees present. Look for stretches on the big rivers where the banks narrow, the water deepens and there are overhanging trees. These key areas should have higher concentrations of moth larva and trout should have them on the food menu. Last but not least, warm-water species of fish love moth larva just as much as trout do. Last year, I spent a day on thw lake bass fishing casting these guys under trees along the banks for bass and bluegill. In prime fishing spots I would get a hook up on just about every cast. If you’re interested in doing this tie on a small balsa popper and drop a moth larva pattern 30-36″ off the back. Add a small split-shot if needed, and it’s game ON.

Klewein’s Moth Larva Fly Recipes

Giant Oak Leaf Caterpillar

Hook: TMC 5262 Size 8 or MFC Wide Gap Curved 7181 Size 6
Thread: UTC 140 Fl. Chartreuse
Underbody: .25 Lead-Free Wrap (3/4 length of hook)
Legs: Fl. Chart. Ultra Chenille
Body: Fl. Chart. Ultra Chenille
Yellow Stripes: Medium Round Yellow Rubber Legs
Ribbing: 1X Monofilament 

San Juan Inch-Worm

Hook: TMC 2487 Size 14
Thread: UTC 140 Fl. Chartreuse 
Body: Fl. Chart. Ultra Chenille
Comment: Trim head half the length of tail

Green Gummy Goodness

Hook: Standard Size 12-14 Nymph Hook
Thread: UTC 140 Fl. Chartreuse
Underbody: .25 Lead-Free Wrap
Body: Spirit River Squirmy Wormies (Neon)
Ribbing: Ultra Wire BR Fl. Chartreuse

Author Notes:

I tie up several different moth larva patterns for the hatch, most of them but not all are mentioned above for your reference. Keep in mind fly anglers can really get away 80 percent of the time fishing the standard San Juan Inch Worm. I tie mine a little longer than some anglers because I think it does a good job imitating both the large oak leaf caterpillar and the smaller inch worm version. For anglers really wanting to match the hatch and fool the smartest of big fish, take the time to tie up several of my big oak leaf caterpillars.

More Related Posts on Hatches

Keep it Reel,

Kent Klewein
Gink & Gasoline
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2 thoughts on “Sunday Classic / The Moth Larva Hatch

  1. Terrific stuff Kent. Catepillars must be working already around here, as I observed a professional fly fishing competition last week and one of the competitors did well with a fl. green grub-looking fly sunk under an indicator. I only saw it from a distance, but it looked more caterpillar size than inchworm.

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