Insects are often concentrated near the top of the mixing layer. Some insects were even flying above the mixing layer. These insects may have reached such altitudes by actively flying through and above the top of the mixing layer, or the dynamics of a prior thermal may have deposited the insects at the higher altitudes. N octurnal atmospheric structure varies from very thin to thick layers. When an insect layer occurs, it is usually associated with some sort of atmospheric structure.
Some atmospheric layers seem to inhibit insects from flying above the layer.