Thrips breeding aggregation.

A thrips (both singular and plural noun) is what we often call a "thunder fly" when they swarm in still, warm, humid weather, getting into our eyes and making us itch as they crawl on our sweaty skin. The largest ones, here, are little more than a millimetre or two long. The black ones are adult males which, apparently, use those powerful-looking forelegs for fighting other males. This species is usually found under bark, on rotting wood and probably feeds on fungal threads and spores.

Done