March Brown

(body length approx. 0.7 cm)

Rhithrogena like to live in fast, clean, & well oxygenated water. So much so that according to Caucci & Nastasi's Hatches II they are fairly scarce in Eastern states, where the water is not necessarily so clean anymore.

The above nymph was grabbed in early March, in faster water. March Browns are clinger nymphs, so are not so likely to be dislodged to become fish food. Note that unlike the specimen above, they typically have three, approximately equal length tails. This one was damaged in shipping.

(body length approx 1.1 cm)

This dun, however was not damaged in shipping... He hatched in mid April, in the early afternoon. The hatch typically occurs from mid March through April (though I've seen stragglers as late as June). The adults typically hatch underwater, and swim up to the surface, where they remain for a few seconds before taking flight. A lot of fun can be had fishing this hatch with a soft hackle pattern in the surface film, or a comparadun of the fish are in the mood.

(body length approx 1.1 cm)

This is a female dun -- note the difference in color with the male above... This is not how you tell that it is a female however -- notice the "grappling hooks" on the end of the male's abdomen above (not the long tails -- just underneath.), then notice that the female doesn't have them. Also, the eyes on the male are much larger than the female's. You can tell the sex of other mayflies this way as well. One assumes fish are equal opportunity eaters, and don't delve into such details.

(body length approx 1.2 cm)

This is the male after it had transformed into a spinner -- which happens in the evening, about 2 days after they hatch (at least this was the case with the few I caught...) Unfortunately the spinners don't provide a useful fall for anglers to fish.

dmason@zebu.uoregon.edu