Think Like a Trout, Act Like a Bug.

Wednesday, June 6, 2012

Sprawlers and Crawlers (and how to avoid the tiddlers)

It was bound to happen sooner or later. The warm weather and recent rains have spiked most rivers into muddy torrents – making this a good time to focus on lake fishing. Admittedly I missed the spring window of opportunity for rivers like the Red Deer and upper NSR this year; instead choosing to ply the local trout lakes.

Local lakes have been fishing good these past two weeks with many nice fish in the three or four year class being caught. Chironomid and Callibaetis hatches have been off and on depending on the weather, and the dragonflies have just started to emerge on most lakes. This past weekend at Chain Lake saw a few dozen adult American Emeralds flying along the shoreline (Cordulia shurtleffii – usually the first species to emerge), and Spiny Baskettails (Epitheca spinigera) should be coming off heavy over the next week or so.

The first hatches of dragonflies are good news for most anglers since the large, active nymphs tend to draw the attention of larger fish (the tiddlers tend to focus more on the midges and mayflies). Trout can be quite gluttonous during dragonfly nymph migrations; I have caught big trout that were stuffed so full of these bugs that the fish were literally regurgitating handfuls of live, squirming nymphs as they were being released. If you want to bypass the newly stocked runts of the year, try working a dragonfly imitation along the bottom – either in 12 to 15’ of water during the day, or in the shallows as dusk approaches.

As far as dragonfly nymphs go, there are basically two types to consider: Sprawlers in the families’ Corduliidae and Libellulidae, and crawlers (sometimes called Darners) in the family Aeshnidae.

Aeshnidae nymphs are long and relatively narrow in profile and are generally seen in shades of brown or dark olive. The nymphs have a two to four year lifecycle and can be up to 50 mm long. These crawlers like to lurk on dead logs and stumps, stalking unsuspecting prey (virtually anything they can subdue – including small minnows). Their preference for woody debris means that they are most often found in shallow water but they occasionally venture deeper if conditions allow.

Aeshna sp. (nymph)
Corduliidae and Libellulidae nymphs have a shorter and wider profile, and are somewhat flattened so they can lie tight to the bottom. Nymphs have a two to three year life cycle and can be up to 30 mm long. Their color tends to match whatever substrate they are on (usually shades of green, olive, brown, or tan). They are also covered in fine hairs that give them a ragged appearance. The hairs also tend to trap sand or silt adding to their camoflage. Sprawlers lie in wait on the bottom for other invertebrates to venture within striking range. These nymphs will often range out into deeper water (as deep as 12-15’).

Epitheca spinigera (nymph) Family: Corduliidae
Regardless of the species, all dragonfly nymphs have internal gills with the gill chamber opening located on the tail end. Their most common mode of travel is a slow crawl but when they need to get somewhere fast (or escape from predators), they can forcefully expel water from the gill chamber giving them jet like propulsion.
I have posted a video of the migrating nymphs (both sprawlers and crawlers) so you can get a sense of how they look and act:


The video should give you a few ideas as far as what flies to use and how to present them. If I have time this week I will post instruction on how to tie two versions of my favorite pattern – the Marabou Dragon.

With the multi-year lifecycles, these nymphs are available to trout year round, making a dragonfly nymph imitation a good searching pattern if nothing else is emerging. When ready to emerge, the nymphs will migrate into shallow water and wait till dark to make their way to shore where they crawl out onto rushes and grasses to emerge under the cover of darkness. It is during these inshore migrations (usually late afternoon to evening) that large trout will key in on the more active and exposed nymphs.


No comments:

Post a Comment