Curiosities: How high can bugs fly?

“We can pick up insects at 5,000 or 6,000 feet,” says Phil Pellitteri of the UW–Madison insect diagnostic lab. “But wind is a big factor in insect movement, and it’s hard to know whether they are flying or drifting.”

Some insects are wingless, and in general, they make a living near the ground, and so have no reason to move higher into the atmosphere.

But many insects use wind as a migration strategy, Pellitteri says. “We have leaf hoppers and aphids blowing up from Louisiana, and moths from Central America that often arrive after a big storm front comes through. Nothing surprises me anymore.”

Although many lightweight insects may catch the wind, behavior may confer an advantage in using the wind, Pellitteri says. “Some of the southern species, like the little leaf hopper, which infests alfalfa, strawberries and potato, have something that functions like a temperature gauge. If the temperature falls below 60 degrees, they drop down. This makes sense. If the wind is from the south, it’s going to be warmer, and they will get a free ride north. When the wind comes from the north, it’s cooler, and they stay put on the ground.”

The result is a ratcheting effect that pushes the leaf-hoppers northward in the spring, Pellitteri says. “These little stinkers can show up at the end of April, or not until the first week of July, depending on the weather.”

With thousands of species able to get a boost from the wind, it’s hard to be specific about how high insects can fly. But if you are on the 15^th floor of an office building and can open the window, “You will get critters coming in, that’s expected,” Pellitteri says. “Even spiders disperse in the wind, using a dragline to catch the breeze.”