The altitude that insects can reach is limited by air density, temperature, and oxygen availability. These factors are interconnected, as the Earth’s gravitational pull weakens with increasing altitude, causing air molecules to spread out and become less dense.
This decrease in air density makes flying more difficult because insects have fewer air molecules to push against with their wings. Similar to humans, insects require oxygen to survive. At an altitude of 6km, oxygen levels drop to less than half of sea level values, significantly hindering an insect’s ability to maintain the rapid wing movements required for flight.
Temperature also plays a crucial role. Fewer air molecules mean less heat generated from molecular collisions. Although temperature fluctuates within different atmospheric layers, there’s a general trend of decreasing temperature with altitude. Between the Earth’s surface and an altitude of approximately 10km, the temperature steadily drops to below -50°C.
Remarkably, some insects have adapted to these challenging high-altitude conditions. Alpine bumblebees residing at altitudes of 3.25km, for example, have evolved unique flight mechanics. They adjust their wing motion, employing a wider arc to generate lift in the thinner air.
Laboratory experiments have revealed that these bumblebees can even fly in simulated conditions mimicking the air density and oxygen levels found at a staggering 9km – surpassing the height of Mount Everest! However, the extreme cold at such altitudes would likely prevent their flight muscles from functioning in real-world scenarios.
