Bulging bellies: Myotis makes meal of meanies






 Q. Let's hear it for bats as an all-natural pesticide. Just how many insects can one hungry bat eat in a night? –B. Stoker


 A. A single little brown bat (Myotis lucifugus) such as found throughout North America can consume 300 to 3,000, says Penn State biologist Michael Gannon. A nursing mother little brown bat eats more than her body weight– up to 4,500 insects. A colony of 1,000 little brown bats, as found in a house attic, eats 2,600 pounds of insects in a summer. Now if you do the math, taking the average mosquito at about six milligrams, then 1,000 mosquitoes weigh 6 grams. Given 454 grams to a pound, you're talking hundreds of millions of insects being consumed by just a single colony of bats.


Q. When a company sells life insurance, it in effect is betting that the person will live a long life; the person bets on dying prematurely. That's fine for a company insuring large numbers of people, but can such a plan ever go wrong on a small scale? –M.O. Omaha


 A. In the mid-1960s a French lawyer struck a deal with his countrywoman, Jeanne Calment, that seemed mutually advantageous– he bought her apartment for a low monthly payment, no money down, providing her with a small pension for her later years, with the understanding that he would not move in until her death, says Bart Holland in What Are the Chances?


 Calment was a native of Arles and had met Van Gogh when she was 13. By the time Charles Lindbergh crossed the Atlantic in 1927, she was 52. So the deal-striking woman was already near 90. The lawyer made payments to her regularly, and after doing so for 30+ years, he died at age 77. His family inherited the agreement, continuing payments until she died at age 122, the oldest on record at the time and 45 years older than the lawyer had been at his death!


Q. What are the chances of seeing a double rainbow? Is any place better than any other to find them? –J. Garland


 A. Actually, "double rainbows" aren't all that rare, says University of Wyoming atmospheric scientist Robert D. Kelly. For the primary rainbow, water droplets refract the sunlight into its constituent colors just like a prism, with the light entering a drop and reflecting once internally off the surface before leaving: refract-reflect-refract.


Secondary rainbows involve two internal reflections– refract-reflect-reflect-refract–so they're fainter than primary rainbows and appear outside the primary bow with colors reversed. (All rainbows appear opposite the sun, the sun behind your head.) Two other double bow features: the sky will appear darker in the area between the two arcs and brighter inside the smaller, primary bow.


Best observation places are away from visibility obstructions and where isolated thunderstorms occur with areas of clearing for the sun to break through to the rainshaft, adds the University of Arizona's Benjamin Herman. The central plains or southwestern U.S. are good bets, and quite good if you persist for a 2-week period of summer.


Q. When a desert sand dune gets noisy, what sound does it make– so loud it can stop conversations of anyone nearby? a) singing b) squeaking c) whistling d) roaring e) booming? – T. E. Lawrence


 A. All of the above have been attributed to "acoustical" dunes over the centuries, with some accounts comparing the sounds to distant thunder or musical instruments, says DesertUSA.com. "Booming" dunes can be heard in the Sahara Desert, parts of the Middle East, Chile, and the Hawaiian Islands.


Even plain beach sand will squeak when compressed with the feet or poked with a stick. How the sounds are produced is not clear, but they occur when hot dry closely packed spherical sand grains of nearly identical size slide over each other, as during a dune avalanche. The stationary sand underneath apparently acts as a sounding board or amplifier to produce the enormous volume.


One good observation point in the U.S. is Nevada's Sand Mountain, whose two dune summits stand about 390 feet (120 meters) above the desert floor. To really appreciate the total effect, climb to a crest and slide down the steep slip face.


"Going down with an avalanche is sort of like riding an escalator, ankle deep in sand. As the sand begins to vibrate, the sound becomes quite loud, like a low-flying B-29 bomber or squadron of World War II vintage fighter planes."


Send STRANGE questions to brothers Bill and Rich at strangetrue@compuserve.com.