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The carbon dioxide you breathe out attracts flying fungus gnats, representing decomposing organic matter, which they need to lay their eggs.
Decomposing plant material releases carbon dioxide, which fungus gnats have learned to equate with the ideal egg-laying environment. The carbon dioxide you breathe out represents a potential breeding opportunity for gnats. They will fly away if you turn your head and hold your breath.
Why Your Breathe Attracts Fungus Gnats to Your Face
The atmosphere comprises nitrogen (78%) and oxygen (21%). Carbon dioxide only represents 0.04% of the atmosphere.
In the microenvironment of the fungus gnat, any increase in CO2 represents an opportunity. Millennia of evolutionary adjustments have taught the gnat that, to survive, it needs to head toward the highest CO2 concentration.
In the gnat’s environment, higher CO2 concentrations represent decomposing organic matter, the ideal environment for laying their eggs.
When fungus gnats come into contact with animals (whose exhaled air is high in carbon dioxide), the gnat is programmed to fly toward the source – the animal’s face.
While we know how irritating it is having these little critters around our faces, and some may know how it hurts when they fly into your eyes, the fungus gnats are only doing what they have learned to do – find the source of CO2 so that they can lay eggs.
By turning your head away from your last breath, you dilute the CO2 concentration and avoid the gnats. Holding your breath will stop the CO2 supply, and the fungus gnats will fly off to some other stimulus.
Fungus gnats are not precisely the best flyers, mainly needing to find the soil to lay their eggs in their 10-day life cycle. Still, their lack of flying skills adds to their being an irritation, though fungus gnats are not the biting kind of gnat.
The Fungus Gnat Life Cycle
- A female fungus gnat can lay up to 300 eggs in clusters of 20 to 30 or more in organically-rich soil (where the level of CO2 indicates microorganisms below).
- Eggs hatch in about six days.
- Larvae feed on fungi, hair roots, and organic matter for 12-14 days before changing into a pupa, formed inside a silken pupal chamber in the soil.
- The pupal stage may last 5 to 6 days, and adults live up to 10 days (in which they must mate and lay eggs).
- The life cycle from egg to adult is approximately 28 days long, depending on temperature – higher temperatures and faster development.
The Ideal Environment for Fungus Gnat Egg Laying
Although they don’t harm people’s health, they can be inconvenient. Fungus gnats can harm potted plants by dispersing fungi and causing damage to the roots and stems if the population grows large enough.
Gnats are frequently an issue in greenhouses because they eat fungus, bacteria, and organic materials in moist potting soil mixtures. Tender roots and shoots may be included in feeding, which could cause damage that would directly or indirectly kill seedlings.
The life cycles of fungus gnats can continue indefinitely, with overlapping generations, in warm indoor environments with ordinary or high humidity.
When female fungus gnats search for a damp growing medium inside, they can spread to other plants and infest them by riding on plants, plant pots, and soil. Examine any plants you bring home from the store, as gifts, or from an office environment.
Avoid overwatering plants since damp soil encourages the survival and growth of these pests. Keep in mind that fungus gnats can infest indoor plants if they enter through open doors and windows because they are outdoor pests.
Decomposing Organic Matter
The two most crucial components for microbial breakdown are carbon and nitrogen. About 50% of microbial cell mass comprises carbon, an energy source and the fundamental building block.
The carbon is broken down into water and carbon dioxide as the microbes consume it. In a sense, photosynthesis is a process that turns the remains of dead organic matter into living organic material.
The plant uses the emitted CO2 to produce food for its growth, while the microbes consume carbon and nitrogen. A sugar chain is created from carbon dioxide (CH2O).
The fungus gnat believes that where there’s smoke, there must be fire, or where there’s carbon dioxide, there must be organic material decomposing fungi. “Yay, food for my offspring!”
Summarizing Why Fungus Gnats Fly In Your Face
Carbon dioxide is a fungus gnat aphrodisiac, so when they’re in your vicinity, and you breathe their favorite smell out, they’re on you like white on rice. It’s their response to the carbon dioxide you exhale – nothing personal.
To completely eradicate fungus gnats, stop the eggs from hatching to prevent the larvae from developing. Failure to proactively fight these insects in their early stage means you’ll keep dealing with the nuisance of adult fungus gnats.
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