Monday, May 2, 2011

Outhouse Entomology

I know most of us don't have the privilege of living on the rivers where we fish, so we may not always be aware of all that goes on in the way of insect life. I stumbled upon an easy way to survey stream insects without ever turning a single rock at the water's edge.

So, here's the secret...

If you want a crash course in the entomology of a particular stream it may be as simple as making a nocturnal pit stop in a lighted outhouse near the water.

Let me explain...

Kelly and I made a trip to the Spring River in Arkansas during Easter weekend. It was a brief, but good trip. We caught lots of fish... Kelly more than I... as usual. We had the river pretty much to ourselves. The bad weather in the area kept the people away I suppose... or maybe they just weren't as foolish as us to be out there. We fished under looming storm clouds with lightning ever present in the distance. We also fished straight through a few brief showers.

On Friday night after we set up our tent, we made our rounds to the campground bathhouse (really just a glorified outhouse). As we took care of our business, we were literally surrounded by a host of stream dwelling insects. We pretty much got to see the full diversity of what's on the menu for the fish. We made a few pretty cool discoveries, and I even saw a few that I did not know inhabited the Spring. The insects were drawn to the lights, and were both outside and inside the building... somebody left the doors open.

Mystery brown mayfly, size 14

Blue-winged Olive (Baetis vagans), size 16

Mystery white mayfly at right, size 14

Light Cahill (Stenacron canadense) at left, size 14

Mystery brown stonefly, size 12

Salmonfly (Pteronarcys sp.), size 8

There were also a fair number of small (size 18 to 16) black and tan Caddisflies, but I didn't get any photos of them.

We all know that insects are drawn to lights, so this may be something that everybody out there already knows... and it certainly isn't a secret, but I felt that maybe I should share this idea. Of course, if your accommodations on the river are a little fancier than a campground with a lighted outhouse, you could probably spend a little time on the porch of the lodge and obtain similar results. If you don't get to routinely sample the hatches on a particular stream, it might give you some ideas about what to expect. On a river like the Spring (and others in Arkansas) hatches are sparse (and never heavy), and it's difficult to learn much from watching what's flying around the river.

I know I'll be adding a few new mayfly emergers and Salmonfly nymph patterns to my Spring River arsenal.

We also found this cool looking critter...

White-lined Sphinx Moth (Hyles lineata)... maybe a size 2

Not all that interesting from a fly fishing perspective, but pretty awesome for two Lepidoptera loving naturalists.

I still don't really understand why insects are drawn to the lights, but it sure makes it easy to find out what the fish are eating in the waters nearby.


  1. In the summer I usually detest walking on the front door at night for the cloud of insects the porch light draws. Many wind up in the house as we open the door. But sometimes I will stand by the light and be blown away by the diversity of insect life that is attracted to the light. Your suggestion is a great idea. And great pictures too.

  2. That is a one heck of a list of visiting insects.

    Thanks for sharing.
    Passinthru Outdoors Blog - Sharing the Passion

  3. Not proven scientifically, but I understand that the reason bugs like the light is, it's easier to read.

  4. Kiwi, there's always a bug trying to get in the house. The "June bug" beetles are the worst.

    Passinthru, there were a lot of cool insects to watch while sitting on the toilet. I only photographed a small sampling of what was in/on the outhouse.

    Cofisher, you're not the first person who has suggested this theory. I actually discovered it by googling "insects attracted to light" last night. It's an interesting idea. Thanks for sharing.

  5. Ephemoroptera's Explanation?!?!?: If my name meant "short-lived," I'd fly towards the light too:). So that explains the mayflies...maybe not the Sphynx moth, though. I'll have to think on that one. Cool post, Jay. I loves me some insects.

  6. Thanks for the insightful commentary, Jen. Sphinx moths are pretty short lived as well... I'm sure they're thinking "fly to the light" so they can get to their next life... the great beyond... or something like that.

  7. Stopped by to check out the latest here- what a novel idea, checking the outhouse. I think they have tying material in there that matches that white fly. Glad you made it through those storms ok, and I think that eating those Kettle chips while fishing smallmouth would kill a lot of birds with one stone. Looks like you're catching a lot more fish than me, so I'd better get out there.

  8. Jason, I'm not sure how well that white tying material would hold up when it gets wet. As far as us catching more fish... I really think that just may be a matter of quantity over quality. I would much prefer some quality at the moment. Thanks for stopping by.

  9. The first time we hit the Arkansas River was shortly after the big caddis hatch. I walked into the outdoors bathroom (better than outhouse) and was engulfed in caddis...kinda cool in a creepy way, but I love it.

  10. Cofisher, too many bugs, even if you're not afraid of them, can be a little creepy. When the walls are literally crawling, even I get a little creeped out... and I play with snakes for fun.