Biological Weapons are weapons of a biological nature, nowadays usually weapons that work though the spreading of diseases and other pests.
Biological warfare can be covert because even a tiny release of organisms can have a huge effect. It can involve either economic warfare with agents targeted at crops or livestock or it can involve organisms that kill human beings.
Almost by definition the modern ones are weapons of mass destruction because once a new infection is released there is no way to prevent from spreading beyond the battlefield and killing civilians, or their food supply. Nor do bacteria, viruses, fungi and insects respond to surrenders or declarations of ceasefire. This means that they are generally considered incompatible with the rules of war.
Historically biological weaponry included such practices as:
- Using catapults to throw beehives and rotting bodies into besieged towns.
- "Poisoning" wells by throwing dead animals into them.
- Dipping weapons such as arrowheads into faeces prior to use.
Modern biological warfare includes or has been alleged to include:
- Anthrax and other natural diseases to which few people have natural immunity.
- Genetically modified diseases.