The Collaborative International Dictionary
Upswarm
Upswarm \Up*swarm"\, v. i. & i.
To rise, or cause to rise, in a swarm or swarms. [R.]
--Shak.
Cowper.
Wiktionary
upswarm
vb. 1 (context transitive English) To rise in a swarm. 2 (context intransitive English) To cause to rise in a swarm.