Mosquitoes are common and known for their persistent biting. Beyond being a nuisance, certain species are vectors for various diseases. Understanding what attracts them and developing control methods are important steps in mitigating their impact.
The Mosquito’s Attraction Cues: What Draws Them In
Mosquitoes, particularly blood-feeding females, use a sophisticated sensory system to locate hosts. Carbon dioxide (CO2), exhaled by humans and animals, is a primary attractant. Mosquitoes detect this gas using specialized receptors on their antennae and maxillary palps, tracking a CO2 plume from 10 to 50 meters. This cues their host-seeking behavior.
As a mosquito approaches a potential host, other cues become increasingly important. Body heat serves as a close-range attractant, guiding mosquitoes to within a few inches to 2.5 feet of a target. They possess heat-sensing neurons in their antennae, which help them pinpoint the warmest areas, typically where blood vessels are closest to the skin’s surface.
Skin odors, a complex mixture of volatile organic compounds (VOCs), also play a significant role in attracting mosquitoes. These compounds are produced by skin bacteria breaking down substances in sweat. Lactic acid, a prominent component of human sweat, is a notable attractant. Other compounds like ammonia and various fatty acids also contribute to the unique human scent profile that draws mosquitoes.
Visual cues further aid mosquitoes in their search, especially after detecting CO2. Mosquitoes are attracted to darker colors such as red, orange, black, and cyan, which stand out against the horizon. This visual attraction is activated by the presence of CO2, guiding mosquitoes from distances of 5 to 15 meters to a potential host where other cues can then take over.
Leveraging Attraction: Smart Trapping and Lures
Understanding what attracts mosquitoes allows for the development of targeted control methods, particularly through smart trapping and lures. Many mosquito traps mimic human exhalation by releasing carbon dioxide (CO2), often generated from propane combustion or CO2 cylinders. These CO2-emitting traps are effective over substantial distances, capable of luring mosquitoes from up to 1.5 acres or 115 feet away.
To enhance trap attractiveness, synthetic human scents are frequently incorporated. Octenol, a common additive, can synergize with CO2, significantly increasing trap catch rates. Lactic acid, a key component of human sweat, is also used in synthetic lures, often combined with other volatiles to create a more compelling human-like scent profile. While lactic acid alone may be a weak attractant, it becomes more effective when combined with CO2 and other compounds.
Once lured into close proximity, various mechanisms are employed to capture and eliminate mosquitoes. Traps may use a powerful fan to suction mosquitoes into a collection net or container, where they then dehydrate. Other designs utilize adhesive surfaces to trap the insects or an electric grid to electrocute them upon contact. Some traps also integrate heat to simulate body warmth, providing an additional close-range attractant that complements the chemical lures.
Light traps, particularly those emitting ultraviolet (UV) light, can attract various insects, but they are generally less effective for mosquitoes when used in isolation. Their efficacy for mosquito control improves when combined with CO2 or other scent attractants, leveraging the multi-sensory approach mosquitoes use to find hosts. Blacklight traps have shown promise in monitoring mosquito populations.
Beyond Traps: Comprehensive Mosquito Control
Effective mosquito management extends beyond attraction-based trapping and involves a broader, integrated approach. A foundational method is source reduction, which focuses on eliminating stagnant water where mosquitoes lay their eggs. This includes routinely emptying and cleaning containers such as buckets, birdbaths, and plant saucers, as even small amounts of water can support mosquito breeding. Inspecting and clearing clogged gutters and ensuring proper drainage around properties are also important steps.
Larvicides offer another targeted approach by controlling mosquitoes in their immature, aquatic stages before they develop into biting adults. Bacterial larvicides, such as those containing Bacillus thuringiensis israelensis (Bti), work by releasing toxins that disrupt the digestive system of mosquito larvae upon ingestion. Insect growth regulators (IGRs), like methoprene, interfere with the larvae’s normal development, preventing them from maturing. Oils and films can also be applied to water surfaces to suffocate larvae and pupae by forming a barrier that prevents them from accessing air.
Personal protection is another aspect of mosquito control, primarily through the use of repellents. These substances deter mosquitoes from landing on the skin. DEET is a widely recognized chemical repellent that interferes with a mosquito’s ability to detect host cues like body heat, CO2, and skin chemicals. Picaridin, a synthetic compound, works by blocking mosquitoes from sensing their prey and offers comparable efficacy to DEET with a milder odor and less potential to damage materials. Other approved repellents include IR3535 and oil of lemon eucalyptus. These methods, when combined, contribute to a more comprehensive strategy for managing mosquito populations.