Mosquito

The deadliest animal alive

Mosquitoes kill more humans than any other animal — by a wide margin. Annual deaths from mosquito-transmitted disease are estimated at over 700,000 globally, mostly children in malaria-endemic regions. By comparison, snakes kill roughly 100,000 per year; humans kill humans at roughly 400,000 per year.

The lethality is entirely about disease transmission, not the bites themselves. Mosquitoes are the world’s most efficient biological needles, carrying:

• Malaria (Plasmodium parasites) — over 600,000 deaths annually.
• Dengue fever
• Yellow fever
• Zika virus
• West Nile virus
• Chikungunya
• Lymphatic filariasis

Only females bite

Male mosquitoes feed exclusively on plant nectar. Females need a blood meal to develop their eggs — protein in blood is essential for egg production. After taking a meal (about 2–3 times their body weight in blood), the female digests it over several days, then lays a clutch of 100–300 eggs. A long-lived female may go through this cycle several times.

Because females are the disease vectors, all mosquito-control efforts target females (or kill larvae before they mature into either sex).

Why some people are mosquito-magnets

Mosquitoes find their hosts using a combination of cues:

• Carbon dioxide in exhaled breath (detected from up to 50 m away).
• Body heat at close range.
• Skin volatiles — lactic acid, ammonia, and over 300 other compounds detected by olfactory receptors.
• Visual cues in good light.

People differ measurably in how attractive they are to mosquitoes — driven by skin microbiome, blood type (type O is preferred over A or B), pregnancy (more attractive), beer consumption (more attractive), and genetics.

Pollinators, occasionally

Despite their reputation, mosquitoes are pollinators of certain flowers — particularly orchids that have evolved to attract them. Both males and females visit nectar sources. The Arctic blunt-leaved orchid is pollinated almost exclusively by mosquitoes.

Eradication efforts

Mosquito populations have been targeted for elimination through:

• Sterile insect technique — releasing sterilized males to suppress breeding.
• Genetic gene drives — engineered genes that spread through populations and impair reproduction.
• Wolbachia infection — releasing mosquitoes carrying a bacterium that prevents virus transmission.
• Bed nets treated with insecticide — the single most cost-effective malaria intervention.

The case of Anopheles gambiae — the principal malaria vector — is especially studied. New CRISPR-based gene drives could in principle suppress entire wild populations within a generation, raising both promise and ethical concern about deliberate species suppression.