The Triumphant Squirrel

Linemen of the Wisconsin Telephone Co. were out on the road last week busily repairing the damage done to telephone cables by one of their most persistent natural enemies: the Sciurus carolinensis, or Eastern grey squirrel. To the engineers of Bell Telephone Laboratories, the problem is old stuff. In an average year, they figure, the grey squirrel gnaws through some half million dollars worth of U.S. cable. So far, no one has found a feasible way to stop him.

A Switch to Salt. Bell Labs' war on the grey squirrel dates back to the turn of the century, when the company first became conscious of the squirrels' appetite for the lead sheath in which telephone wires are encased. After the squirrels gnaw through the sheath, linemen found, moisture gets at the paper insulation around the wires, causing a short circuit and disrupting communications. Engineers went to work to find out what it is in the lead that appeals to squirrels. According to one theory, the squirrels are suffering from a nutritional disorder caused by a lack of calcium and phosphorus in their diet. Engineers put salt disks in containers on telephone poles, found that the squirrels were willing to switch to salt for one year. After that, they went right back to gnawing cables.

According to another theory, only "neurotic" squirrels gnaw. One researcher cooped up a group of squirrels in cages, provided them with all kinds and sizes of cable to chew on (0.5 in. proved most popular). He concluded that young, emotionally unstable squirrels and pregnant squirrels undergoing a change in their nervous systems are the most destructive gnawers. It was not as easy to find a solution, however. Emotionally upset squirrels, the engineers found, do not insist on lead sheaths; they are just as eager to chew on cables wrapped with copper screening or glass tape.

Shocks, Steel & Paint. Over the years, Bell Labs has tested more than 100 squirrel deterrents. Among them: weasel scent, tree paint, rabbit repellent, electric shock devices, steel-tape armor, 24-in. barriers of galvanized iron on telephone poles. None of these measures have worked. Several years ago, a researcher thought he had the answer in a brand-new repellent made of chlorinated hydrocarbon, found that its only effect was to make the squirrels chew treated cables and ignore the untreated ones. Lethal measures, e.g., coating the cables with paint containing ground glass, were blocked by protests from the A.S.P.C.A.

After a half century of combating the grey squirrel, the experts are ready to give up. It is cheaper to treat the damage, Bell Labs has decided, than to try to prevent it. Said Engineer Smith last week, noting the reports of squirrel assaults on Wisconsin cable: "It's hopeless; we're suspending study of the problem."

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