Google+  Facebook  Twitter  Instagram  LinkedIn

UC Santa Barbara
Department of Geography
UC Santa Barbara
Department of Geography
News & Events Department News Events Calendar Event Photos News Favorites News Archive Colloquia Archive
If you would like to be on our mailing list of latest news postings which goes out about every two weeks, or if you have anything relating to the Department that you consider noteworthy, interesting, or just plain fun that you would like to share, please contact the news editor at


UC Santa Barbara Geography / News & Events / Department News

May 11, 2011 - Bat Bombs: "Die Fledermaus Farce"

Bat Bomb Ingredients:

  • 180 Mexican free-tailed bats
  • 180 miniature incendiary bombs (oblong, nitrocellulose cases filled with thickened kerosene) weighing 17 grams each which will burn for 4 minutes with a 10 inch flame or 180 of them weighing 28 grams each which will burn for 6 minutes with a 10 inch flame)
  • 180 small time-delay igniters, cemented to each bomb case along one side
  • 1 cardboard container with a parachute that will open automatically in midair at about 1,000 feet when dropped from a B-25 flying at 5,000 feet

Bat Bomb Instructions

  • Place bats in refrigerators to induce temporary hibernation
  • Attach bomb cases and igniters to the loose skin on each bat's chest with a surgical clip and a piece of string
  • Pack bats into the cardboard container
  • Repeat the above until you have about 3,500 bat bombs
  • Using a B-25 flying at 5,000 feet, drop the bat bombs over a city at night
  • When the parachutes deploy at 1,000 feet, the bats will awaken in the warmer air, fly out of the cardboard boxes, spread out from the point of release, and, at dawn, will hide in buildings across the target city. Shortly thereafter, the time-delay igniters will set off the incendiary bombs, causing widespread fires and chaos (and, sad to say, killing the bats)

The above procedure, using dummy bombs, was sanctioned by President Roosevelt and carried out by the U.S. Army on May 21, 1943 in the desert near Muroc Lake, California, in an effort to find an effective way to burn Japanese cities to the ground. According to Air Force Magazine, “The [first] tests were not successful; most of the bats, not fully recovered from hibernation, did not fly and died on impact. The bat-bomber research team was transferred a few days later to an Army Air Forces auxiliary airfield at Carlsbad, N. M.” Further tests were made, but “there were many complications. Many bats didn't wake up in time for the drops. The cardboard cartons did not function properly, and the surgical clips proved difficult to attach to the bats without tearing the delicate skin. When these problems were somewhat resolved, new bats were taken up for drop tests with dummy bombs attached. Many simply took advantage of their freedom to escape or refused to cooperate and plummeted to earth.”

“It was envisioned that ten B-24 bombers flying from Alaska, each carrying a hundred shells packed with bomb-carrying bats could release 1,040,000 bat bombs over the target—the industrial cities of Osaka Bay." Accordingly, further refinements were made, and another series of tests were conducted. "In one incident, the Auxiliary Army Air Base in Carlsbad, New Mexico, was set on fire when armed bats were accidentally released. The bats incinerated the test range and roosted under a fuel tank. Following this setback, the project was relegated to the Navy in August 1943, who renamed it Project X-Ray, and then passed it to the Marine Corps that December...After several experiments and operational adjustments, the definitive test was carried out on a mockup of a Japanese city built by the Chemical Warfare Service at their Dugway Proving Grounds test site in Utah."

"Observers at this test produced optimistic accounts. The chief of incendiary testing at Dugway wrote: ‘A reasonable number of destructive fires can be started in spite of the extremely small size of the units. The main advantage of the units would seem to be their placement within the enemy structures without the knowledge of the householder or fire watchers, thus allowing the fire to establish itself before being discovered.’ The National Defense Research Committee (NDRC) observer stated: 'It was concluded that X-Ray is an effective weapon.' The Chief Chemist’s report stated that on a weight basis X-Ray was more effective than the standard incendiary bombs in use at the time. ‘Expressed in another way, the regular bombs would give probably 167 to 400 fires per bomb load where X-Ray would give 3,625 to 4,748 fires’” (source).

"Further tests were scheduled for the summer of 1944, but the program was cancelled by Fleet Admiral Ernest J. King when he heard that it would likely not be combat-ready until mid-1945. By that time, it was estimated that $2 million had been spent on the project. It was thought that development of the bat bomb was moving too slowly, and Project X-Ray was overtaken in the race for a quick end to the war by the Manhattan Project. Dr. Lytle S. Adams, who conceived the idea and was recruited to research and obtain a suitable supply of bats, maintained that the bat bombs would have been effective without the devastating effects of the atomic bomb. He is quoted as having said: 'Think of thousands of fires breaking out simultaneously over a circle of forty miles in diameter for every bomb dropped. Japan could have been devastated, yet with small loss of life'” (Ibid.)

Editor’s note: The infamous "Invasion by Bats" project was afterwards referred to by Dr. Stanley P. Lovell, director of the Office of Strategic Services (OSS) as "Die Fledermaus Farce" (Wikipedia: Bat bomb).

Article by Bill Norrington

Image 1 for article titled "Bat Bombs: "Die Fledermaus Farce""
Four biological factors gave promise to the use of bat bombs. First, bats occur in large numbers (four caves in Texas are each occupied by several million bats). Second, bats can carry more than their own weight in flight (females carry their young—sometimes twins). Third, bats hibernate, and while dormant they do not require food or maintenance. Fourth, bats fly in darkness, then find secluded places (often in buildings) to hide during daylight. (Wikipedia: Bat bomb; illustration by Chris Fauver, Air Force Magazine)
Image 2 for article titled "Bat Bombs: "Die Fledermaus Farce""
Cardboard cartons with parachutes designed to deploy at 1,000 feet would release the bats (Chris Fauver, Ibid.)
Image 3 for article titled "Bat Bombs: "Die Fledermaus Farce""
Bat-bomb canister later used to house the hibernating bats. Ideally, the canister would be dropped from high altitude over the target area, and as the bomb fell (slowed by a parachute), the bats would warm up and awaken. At 1,000 ft. altitude, the bomb would open and over a thousand bats, each carrying a tiny time-delayed napalm incendiary device, would fly in a 20-40 mile radius and roost in flammable wooden Japanese buildings. The napalm devices would ignite simultaneously, and thousands of small fires would flare up at once (photo from Bat Bomb: World War II's Other Secret Weapon, by Jack Couffer, University of Texas Press, 1992)
Image 4 for article titled "Bat Bombs: "Die Fledermaus Farce""
Errant bats set the Army Air Base in Carlsbad, New Mexico on fire (Ibid.)
Image 5 for article titled "Bat Bombs: "Die Fledermaus Farce""
Several bats were considered for the project. The largest bat found was the mastiff, which has a twenty-inch wingspan and could carry a one-pound stick of dynamite. However, the team found there weren't sufficient numbers available. The more common mule-eared, or pallid, bat could carry three ounces, but naturalists determined it wasn't hardy enough for the project. Finally, the team selected the free-tailed bat. Though it weighed but one third of an ounce, it could fly fairly well with a one-ounce bomb (Air Force Magazine)
Copyright © 2014 University of California, Santa Barbara | The Regents of the University of California | Terms of Use
ADA accessibility reviewed March 2014. If any of this material is not accessible to you, please contact our department at (805)893-3663 or contact
and we will provide alternatives.

Google+  Facebook  Twitter  Instagram  LinkedIn