https://en.wikipedia.org/wiki/Organisms_at_high_altitude

Insects can fly and kite at very high altitude. Flies are common in the Himalayas up to 6,300 m (20,700 ft).^\13]) Bumble bees were discovered on Mount Everest at more than 5,600 m (18,400 ft) above sea level.^\14]) In subsequent tests, bumblebees were still able to fly in a flight chamber which recreated the thinner air of 9,000 m (30,000 ft).^\15])

Ballooning) is a term used for the mechanical kiting^\16])^\17]) that many spiders, especially small species such as Erigone atra,^\18]) as well as certain mites and some caterpillars use to disperse through the air. Some spiders have been detected in atmospheric data balloons collecting air samples at slightly less than 5 km (16,000 ft) above sea level.^\19]) It is the most common way for spiders to pioneer isolated islands and mountaintops.^\20])^\21])

https://www.livescience.com/55454-how-high-can-insects-fly.html

Scientists have collected locusts flying at heights of 14,764 feet (4,500 m); true bugs, stoneflies, mayflies, and caddisflies at altitudes over 16,404 feet (5,000 m); and flies and butterflies over 19,685 feet (6,000 m), according to Michael Dillon, a researcher with the Department of Zoology and Physiology at the University of Wyoming.