Every year, mosquitoes kill more people than any other creature in the world. Because of 1) mosquitoes’ ability to spread deadly, communicable diseases and cover large distances quickly, and 2) the fact that different types of bugs have been weaponized for hundreds of years, it is not surprising that mosquitoes have been used as weapons or suspected of being used as weapons.

One of the most well known examples of mosquitoes being used as biological weapons occurred in the 20th century during World War II. Nazi researchers studied insects, including mosquitoes, to determine their ability to spread disease. The Nazi forces then went to Italian marshes to purposely collect mosquitoes with malaria and them into the population. 

While this is the most well-known case of using mosquitoes as biological warfare, the use or considered use of mosquitoes as weapons is not unique to Germany. For instance, Fort Detrick in Maryland was created during World War II to focus on defending the United States against biological weapons and researching biological weapons. One plan for the site in the late 1950s involved releasing mosquitoes infected with yellow fever virus against an enemy though this never actually happened.

Several militaries, research facilities, universities, governments, and other entities have also explored mosquitoes as potential bioterrorism weapons. However, most researchers now claim that aerosolized viruses are more impactful than mosquitoes despite the fact that they are also more costly. 

Advances in technology have also changed the possibilities when it comes to the potential use of mosquitoes as biological warfare. For instance, the ability to genetically modify mosquitoes is a major advance in the field of bioterrorism. 

Though mosquitoes can be modified to be even more successful at spreading viruses, there are many challenges associated with this approach to biological warfare:

• Mosquitoes can travel relatively quickly, meaning it would be hard to contain those more dangerous mosquitoes to one targeted area
• Genetic modifications might jump from one species to another
• Translating ideas from the laboratory into real life populations is challenging, meaning it’s difficult to know how successful or dangerous the approach would be
• Climate change may alter mosquito behaviors and geographies, adding more uncertainty and challenge to this approach 

Many other obstacles must be considered in addition to the ethical issues scientists face. This is particularly the case as the consideration of using mosquitoes at a large scale is not limited to spreading viruses that mosquitoes already carry – it is also likely possible that mosquitoes can be used to spread toxins or other substances that aren’t typically carried by mosquitoes. 

The use of mosquitoes at scale can also be to benefit populations rather than harm them. Some nations like Brazil, for instance, are working on fighting viral epidemics by using genetically modified mosquitoes. Some researchers have also considered using mosquitoes to improve a population’s immune system by adding a genetically modified bacteria that has the ability to activate a person's immune system against diseases like malaria. Mosquitoes have also long been used as methods for controlling disease spread; and releasing sterile male mosquitoes into larger populations has been used for many years to reduce or eradicate insect populations as well as to deliver viruses or pesticides to breeding grounds through mosquitoes to reduce populations.

The use of mosquitoes in biological warfare is a violation of The Biological Weapons Convention, which "effectively prohibits the development, production, acquisition, transfer, stockpiling and use of biological and toxin weapons" which are considered weapons that "disseminate disease-causing organisms or toxins to harm or kill humans, animals or plants."

A recent patent utilizing drones that release mosquitoes infected with a toxin was circulated around the internet. This prompted many to become alarmed about the use of mosquitoes as a bioterrorism weapon in Ukraine and beyond.