Swarm
WordNet
noun
(1) A group of many insects
"A swarm of insects obscured the light"
"A cloud of butterflies"
(2) A moving crowd
verb
(3) Move in large numbers
"People were pouring out of the theater"
"Beggars pullulated in the plaza"
(4) Be teeming, be abuzz
"The garden was swarming with bees"
"The plaza is teeming with undercover policemen"
"Her mind pullulated with worries"