Insects require other adaptations to achieve some independence from the surface strata. Some insects manage to exploit deeper reaches of water by carrying air stores along with them during their dives. This strategy is well developed in the predacious diving beetle Dytiscus . By keeping air stores in contact with spiracles during a dive, these beetles have their trachael systems plus air stores to draw upon to meet oxygen requirements. Spiracles are typically located along the sides of many terrestrial insects, but this arrangement does not help much with carrying supplies of air under water.
Many beetles have their abdominal spiracles on the dorsal surface, under the elytra.
This needs be only slightly adjusted for carrying air stores during diving. Many other insects, especially aquatic true bugs also carry air stores under water. The efficacy of the air store is vastly improved because the bubble itself can act as a physical gill. That is, it can extract oxygen directly from the surrounding water. The following work on the backswimer Notonecta illustrates the point.