What Is the Deadliest Insect on Earth?

A female Anopheles freeborni.
This female Anopheles freeborni is taking a blood meal from a human host by pumping the ingested blood through her labrum, which is visible here as a thin red, needle-like structure between the mosquito's head and the host's skin. CDC/ James Gathany

Though the vast majority of insects do us no harm, and, in fact, make our lives better, a few insects exist that can kill us. Which is the deadliest insect on Earth? 

You may be thinking of killer bees or maybe African ants or Japanese hornets. While all of these are certainly dangerous insects, the deadliest is none other than the mosquito. Mosquitoes alone can't do us much harm, but as disease carriers, these insects are downright lethal.

The Deadliest Insect: Malaria Mosquitos

Infected Anopheles mosquitoes carry a parasite in the genus Plasmodium, the cause of the deadly disease malaria. That is why this species is also known as the "malaria mosquito" though you might also hear them called the "marsh mosquito."

The parasite reproduces within the mosquito's body. When female mosquitoes bite humans to feed on their blood, the parasite is transferred to the human host.

As vectors of malaria, mosquitoes indirectly cause the deaths of almost one million people each year. According to the World Heath Organization, about 212 million people suffered from the debilitating disease in 2015. Half the world's population lives at risk of contracting malaria, particularly in Africa where 90 percent of the world's malaria cases occur.

Young children under the age of five are in the most danger. It's estimated 303,000 children died of malaria in 2015 alone.

That is one child every minute, an improvement of one every 30 seconds in 2008.

Yet, in recent years, malaria cases have declined thanks to a number of intervention methods. This includes the use of insecticides on mosquito nets and indoor spraying in the areas that are most affected by malaria. There has also been a significant increase in artemisinin-based combination therapies (ACTs), which are very effective in treating malaria.

Mosquitoes That Carry Other Diseases

Zika has quickly become the latest worry among mosquito-caused diseases. Though deaths in those affected with the Zika virus are rare and often the result of other health complications, it's interesting to note that other species of mosquito are  responsible for carrying it.

Aedes aegypti and Aedes albopictus mosquitoes are the carriers of this virus. They are voracious daytime feeders, which may be why so many people were infected so quickly when the outbreak really took hold in South America during 2014 and 2015.

While malaria and Zika are carried by select species of mosquitoes, other diseases are not as specialized. For instance, the Center for Disease Control and Prevention (CDC) has listed over 60 species that can transmit the West Nile virus. The organization also notes that Aedes and Haemogugus species are responsible for most yellow fever cases.

In short, mosquitoes are not merely pests that cause nasty red bumps on your skin. They have the potential cause a serious illness that can lead to death, making them the deadliest insect in the world.