NOW HERE IS a controversy worth thinking about. It comes from an article by R. Jeffrey Smith in a forthcoming issue of Science magazine, and it concerns a serious dispute between the Environmental Protection Agency and the manufacturers of electromagnetic insect and rodent repellers. According to the article, these allegedly better mousetraps are "the answer to an exterminator's prayers," at least insofar as such prayers pertain to exterminations. By a complicated process they create air waves in the magnetic field of the earth that are said to be so nerve-wracking to rats, mice and cockroaches, that the creatures become confused to the point of not eating, drinking, reproducing or doing any of the things that make life worth living.

The concept behind this procedure is known as "contro-clusive magnetism." It is known that way to George Fiedler, president of Solara Products (which makes a repeller with the pleasant name of Nature Shield, pleasantly priced at $1,195), who picked up the idea from Robert Brown, a manufacturer of electric guitars. Like Roentgen who discovered the X-ray by lucky accident, Mr. Brown discovered contro-clusive magnetism. It seems he thoughtlessly miswired one of his guitars and left it plugged in overnight in his garage. When he returned the next day he discovered "several dead rodents," whose condition he attributed to the guitar. At that happy moment he gave up music for extermination.

None of this charms the EPA. A year and a half ago the agency conducted $100,000 worth of tests on the repellers, found them worthless and ordered three brands taken off the market. Mr. Fiedler protests. He claims to have "hundreds of satisfied customers all over the world" - presumably human. And some of the customers are very impressive indeed. They include our own National Press Club, our own Hay-Adams Hotel, and our own U.S. Senate office buildings, whose superintendent purchased six repellers only last year. The Senate reported a "significant reduction in complaints about rodents from senators' offices." And while it is hard to imagine that there ever were pests in the National Press Club, There, too, are tales of success.

You don't need to decide between the EPA and the Senate or the National Press Club to see that there is much to be said for the idea that air waves cause severe, perhaps fatal confusion. For example, Mr. Fiedler explains contro-clusive magnestism as "a multiple vortex energy flow resolving in an elastic expansion and capacitance in relation to space and attitude." You and we would not be confused by such talk, but a rat is something else.