I was checking on some cattle tanks I use to rear dragonflies (I'm an aquatic ecologist) when I noticed swarms/aggregates of little "flies" flying around on top. I noticed some of them had crawled down into the water and were walking around on the algae attached to the side of the tank. They would crawl under water for a short while and then reemerge. I assumed they were mating swarms of flies with an aquatic larval stage and the ones under water were laying eggs. However, on closer inspection I realized they were hemipterans (my best guess is chinch bugs/Blissus). As far as I am aware, chinch bugs don't have an aquatic stage, and most references of them and water indicate that flooding is a way to control infestations of them, so I'm very curious about what they were doing under the water. Does anyone more familiar with chinch bugs have any ideas?

Cattle tanks were on a tennis court next to old field habitat and close to a large pond.