Four New Blood-Sucking Flies Found in Doñana Marshes, Not Mosquitoes 2026

In the heart of the Guadalquivir marshes, researchers searching for the mosquito that carries West Nile virus instead found four new species of blood-sucking flies. The discovery, made during Spain's largest entomological surveillance operation, highlights the unexpected biodiversity hidden in one of Europe's most studied wetlands.

The team, from the Spanish National Research Council (CSIC) and the University of Milan, was targeting mosquitoes but instead captured biting midges—tiny two-millimeter insects that have been biting Europeans for millions of years without notice. The finding raises important questions about insect monitoring and public health.

What Exactly Was Found in Doñana?

During sampling in the Doñana marshes, researchers identified four completely unknown species of hematophagous biting midges, and found four additional species already known to science, bringing the total to eight. This is the first time this genus has been recorded in Andalusia.

The midges belong to the family Ceratopogonidae, which are true flies. Unlike mosquitoes, these midges bite during the day and thrive in sandy soils, dunes, and marshes where their larvae develop. Their bites create small pools of blood that they then feed on.

Why Is This Discovery Significant?

The fact that new species were found in Doñana—a region that has been intensively studied for decades—underscores how much remains unknown about insect diversity even in well-researched areas. The researchers were part of a large-scale surveillance program aimed at detecting West Nile virus vectors, but the traps yielded unexpected results.

This finding suggests that current monitoring efforts may overlook other blood-feeding insects that could play a role in disease transmission. While biting midges are not known to transmit West Nile virus, some species can carry other pathogens affecting humans and animals.

What Are Biting Midges and Why Do They Matter?

Biting midges are small flies, often called "no-see-ums" due to their tiny size. Females require a blood meal for egg production, and their bites can cause itchy welts and, in some cases, allergic reactions. They are also vectors for diseases such as bluetongue virus in livestock and Oropouche virus in humans.

In Europe, biting midges have been linked to the spread of bluetongue, a disease that affects sheep and cattle. The presence of new species in Andalusia could have implications for local agriculture and animal health. The background to this story is set out in West Nile Virus Surveillance: Chickens as Early Warning Systems. A related thread runs through Biting Midges: Who Knows the Rhagionidae?. Earlier coverage in East Frisian Islands: Mudflats, Marshes, and Millions of Birds shows how the argument developed.

Key Takeaways from the Doñana Study

• Four new species of blood-sucking biting midges were discovered in Doñana.
• The find occurred during surveillance for West Nile virus mosquitoes.
• This is the first record of the genus in Andalusia.
• Biting midges are active during the day and breed in sandy, marshy soils.
• The discovery highlights gaps in insect monitoring even in well-studied areas.

Comparison of Mosquitoes and Biting Midges

What Does This Mean for Public Health?

The discovery does not immediately suggest a new disease threat, but it emphasizes the need for broader entomological surveillance. Current programs focus on known vectors like mosquitoes, but other blood-feeding insects may be equally important. A closer look at the same subject appears in Climate Crisis Heat Is Sucking Europe's Soils Dry – Extreme. Anyone following the wider picture can start with Climate Crisis Drought: Heat Sucking Soils Dry Across Europe. The same theme surfaces in Energy Utilities: latest articles, which takes a different angle.

Researchers recommend expanding monitoring to include biting midges and other understudied groups. This could improve early detection of potential disease vectors and inform public health strategies. Context on how this played out before sits in What Exactly Is a Heat Wave? AEMET's Golden Rule for Spain. A companion piece, Invasive Asian Seaweed Becomes Superfood for Fish in Spain, approaches the same subject from another angle.

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