It was Doc who first noticed Dud's strange behavior. 

I was too busy trying to drop an elk-hair caddis fly, size 16, just beyond that big smooth rock on Lewis Creek. I know there's a big rainbow trout in that hole there, you see, and there is nothing more important, on a summer morning like this one, than enticing that big rascal into delivering himself to my waiting hands.

But Doc noticed that Dud had laid his fly rod down in the bushes and was doing strange things with his hands. Finally, Doc got my attention, pointed to Dud, and we both stopped fishing and walked over to see what our long-time pal was up to.

Dud would look around in the air, then make a one-handed grab at the air. After several grabs, he'd take two fingers of his other hand, put them in his clenched fist, and wiggle around. Then he'd smile and open his fist and look in the air again. Doc and I looked silently at each other, wondering how long it would take from our day of fishing to get Dud delivered to the nervous hospital in the city.

"Dud," said Doc, "how's the fishing?"

"Huh? Oh hi. Not fishing right now, Doc. Experimenting."

"Experimenting?" I said. Of course, I said this automatically, forgetting for a moment how time consuming it could be to start Dud explaining things of a scientific nature.

"Natural selection," Dud said, proudly. "Survival of the fittest. Yes, I decided to spend my morning in Darwinian pursuits, making the world a safer place for mankind."

Doc looked at me. "He's talking like that again," he said.

"Well, Doc," said Dud, "you, of all people, should be able to appreciate what I'm doing. After all, you're a man of science and a healer. I'm going to rid the world of dangerous diseases. Observe."

Then Dud made another grab at the air, and this time we could see he was snatching a mosquito out of the air. Again he used his other hand to do something to the mosquito, and then he released it.

"I'm pulling out their drillers," Dud said. "I figgered if I pull out enough drillers, then sooner or later two drillerless mosquitoes will get married and have pups and then we'll have a family of drillerless mosquitoes here on Lewis Creek. Without drillers, they won't be able to pass along yellow fever or malaria to fishermen."

Doc looked at him in a strange way. "Dud, there's never been anyone get malaria from these Lewis Creek mosquitoes."

"See?" Dud said, brightly. "It's already working."