PLAYING host to 250,000 bats is the queer but profitable hobby of Milton F. Campbell, of San Antonio, Tex. His lakeside bat hotel, a tall wooden tower shaped like the base of a windmill, is the outgrowth of experiments begun years ago by his father, Dr. Charles A. R. Campbell, at that time city bacteriologist of San Antonio. Believing that bats would rid the area of malaria-carrying mosquitoes, Dr. Campbell spent years trying to induce the creatures to settle in a wooden roost which he constructed near the city sewage plant. Finally, by means of ear-splitting phonograph records, which drove the bats from their accustomed haunts, he effected their transfer to his specially constructed tower.
Soon afterwards, residents of the region began to notice a decrease in the number of mosquitoes. A single bat, Dr. Campbell discovered by dissection studies, will consume as many as 3,750 of these pests during a single night’s feeding. Since its introduction, the Campbell bat roost has been a source of revenue as well as a laboratory for the study of the strange little creatures it houses. Visiting bats, tens of thousands of them that choke the interior and often hang in great bunches from the outside eaves, pay their rent by adding to the accumulation of guano in the roost.
Once a year, Campbell cleans this deposit from the interior, raking it down a chute at the bottom and sacking it up for sale. Bat guano is said to be a nearly perfect fertilizer. Sampled and labeled, as required by law, it sells for from five to ten cents a pound. Last year, the roost yielded nearly 6,000 pounds of guano. In fact, so profitable has the unique venture become that quantities of the special lure used for attracting bats, and detailed plans for establishing similar roosts, have been sold to prospective bat raisers in several parts of the country, with an eye to both profit and mosquito control.