They sometimes form dense swarms with up to 500 individuals per square metre.

On the second day we reached Konotop, in a dense swarm of troops looking for transport.

They are generally found in the damp habitats favoured by their host fungi and sometimes form dense swarms.

They often form dense migratory swarms, which may cause panic among people for their resemblance to wasps.

A dense swarm of flies did a crazed dance above them.

Through her tears, she watched the dense swarm disperse as if blown by a mighty gust.

The resulting dense swarm of phytoplankton is called an algal bloom.

Their dense swarms have also become problematic for scientific trawls and water intake.

Their tendency to aggregate creates locally dense swarms up to several square meters in area.

It often feed at night when dense swarms of plankton more up towards the surface.