Canisters packed with poisonous varieties of scorpion are being blasted into towns and villages, which explode on impact - scattering the scorpions and causing panic among the innocent local population.
Although scorpion bombs sound like something out of a modern horror movie, the tactic is actually thousands of years old and was first used by Iraqis fighting against the Roman Empire.
Hamish de Bretton-Gordon, ex-head of chemical and biological weapons for the Army and Nato, told that ISIS had improvised devices to launch the poisonous creatures in 2ft bombs.
He said: 'Scorpions are robust – even if they are launched a couple of miles, when the canister breaks thousands are flung out and start crawling all around.
'Some scorpions are very poisonous but the main thing is creating fear.'
Mr de Bretton-Gordon, who returned from Baghdad last week where he was advising security forces, said that the bombs are not causing casualties but had a profound 'psychological impact'.