Butterfly Bomb A Butterfly Bomb ( or Sprengbombe Dickwandig 2 kg or SD2 ) was a German 2 kilogram anti - personnel submunition used by the Luftwaffe during the Second World War . It was so named because the thin cylindrical metal outer shell which hinged open when the bomblet deployed gave it the superficial appearance of a large butterfly . The design was very distinctive and easy to recognise . SD2 bomblets were not dropped individually , but were packed into containers holding between 6 and 108 submunitions e . g . the AB 23 SD - 2 and AB 250 - 3 submunitions dispensers . The SD2 submunitions were released after the container was released from the aircraft and had burst open . Because SD2s were always dropped in groups ( never individually ) the discovery of one unexploded SD2 was a reliable indication that others had been dropped nearby . This bomb type was one of the first cluster bomb s ever used in combat and it proved to be a highly effective weapon . The bomb containers that carried the SD2 bomblets and released them in the air were nicknamed the " Devil ' s Eggs " by Luftwaffe air and ground crew . Description . The SD2 submunition was an long cylinder of cast iron , which was slightly larger in diameter before its wings deployed . A steel cable 15 cm long was attached via a spindle to an aluminium fuze screwed into the fuze pocket in the side of the bomblet . The outer shell was hinged and would flip open as two half - cylinders when it was dropped . Additionally , spring - loaded wings at the ends would flip out . The wings at the end were canted at an angle to the airflow , which turned the spindle ( connected to the fuze ) anti - clockwise as the bomblet fell . After the spindle had revolved approximately 10 times ( partially unscrewing itself from the bomb ) it released a spring - loaded pin inside the fuze , which fully armed the SD2 bomb . The wings and arming spindle remained attached to the bomb after the fuze had armed itself , as the bomb descended towards the ground . Butterfly bombs contained 225 grams of TNT . They were generally lethal to anyone within a radius of and could inflict serious shrapnel injuries ( e . g . deep penetrating eye wounds ) as far away as . Butterfly bombs were usually painted either dark green or grey . A dull yellow colour scheme was sometimes used , either for use in the Middle East , or when dropped on grain crops at harvest time to kill farm - workers . Butterfly bombs could be fitted with any one of three fuzes , which were made of aluminium and stamped with the model type surrounded by a circle : Butterfly bombs in a submunitions container could have a mixture of different fuzes fitted to increase disruption to the target . Additionally , when a single fuze type with two operating functions was fitted ( e . g . type 41 ) , bombs in a submunitions container could have either or both possible fuze settings selected . Fuze variants such as the 41A , 41B , 70B1 , 70B2 , etc . , also existed . These variants were inserted into the fuze pocket via a bayonet fitting ( the fuze was held in place via two steel clips ) but otherwise functioned identically . As with more modern cluster bombs , it was not considered practical to disarm butterfly bombs which had fully armed themselves but failed to detonate . This was because SD2 fuzes were deliberately designed to be extremely difficult and dangerous to render safe once they had armed themselves . Instead , the standard render safe procedure for any unexploded SD2 butterfly bomb was to evacuate the area for at least 30 minutes ( in case the bomblet was fitted with a type 67 time delay fuze ) , then surround it with a ring of sandbags ( to cushion the explosion ) and destroy it " in situ " by detonating a small explosive charge beside it . Other solutions were to attach a long string to the bomb and tug on it after taking cover , or for bombs in open countryside , shooting at them with a rifle from a safe distance . Not all unexploded SD2 butterfly bombs still have their wings attached . In some cases the wings have rusted away and fallen off . The SD2 then resembles a rusty tin can with an aluminium disc ( the fuze ) in its side , sometimes with a short stub projecting from it . Regardless of age and condition , all unexploded SD2s remain highly sensitive to disturbance and can easily detonate . Use . Butterfly bombs were first used against Ipswich in 1940 , but were also dropped on Grimsby and Cleethorpes in June 1943 , amongst various other targets in the United Kingdom . They were subsequently used against Allied forces in the Middle East . The British Government deliberately suppressed news of the damage and disruption caused by butterfly bombs in order not to encourage the Germans to keep using them . On October 28 , 1940 some butterfly bombs that had incompletely armed themselves were discovered in Ipswich by British ordnance technicians Sergeant Cann and 2nd Lieutenant Taylor . By screwing the arming rods back into the fuzes ( i . e . the unarmed position ) the two men were able to recover safe examples to reverse engineer . The SD2 saw use in the opening stages of Operation Barbarossa , the German invasion of the Soviet Union , which began on 22 June 1941 . Twenty to thirty aircrews had been picked to drop SD2s and SD10s ( 10 kg submunitions ) on key Soviet airfields , a flight of three aircraft being assigned to each field . The purpose of these early attacks was to cause disruption and confusion as well as to preclude dispersion of Soviet planes until the main attack was launched . It was reported that Kampfgeschwader 51 had lost 15 aircraft due to accidents with the SD2s , nearly half of the total Luftwaffe losses that day . The last recorded death from a German butterfly bomb in England occurred on November 27 , 1956 , over 11 years after the Second World War ended : Flight Lieutenant Herbert Denning of the RAF was examining an SD2 at the " Upminster bomb cemetery " ( some remote sandpits situated East of RAF Hornchurch , where EOD experimental and research work took place ) when it detonated . He died of shrapnel and blast injuries at Oldchurch Hospital the same day . Deaths have also been recorded on the Island of Malta as late as 1981 when Paul Gauci , a 41 - year - old Maltese man , died after welding a butterfly bomb to a metal pipe and using it as a mallet , thinking it was a harmless can . The latest find of such a bomb was on 28 October 2009 , by an 11 - year - old boy in a secluded valley close to a heavily bombarded airfield . This bomb was safely detonated on - site by the Armed Forces of Malta . US copy . The United States manufactured a copy of the SD2 for use during World War II , the Korean War and Vietnam War , designating it the M83 submunition . The fragmentation bomblet was used in the US M28 and M29 cluster bomb s .