1.swarm用作名词时意思是“一大群”,转化为动词意思是“群集”,指密密麻麻的昆虫(如蜜蜂、蚂蚁)成群飞离蜂巢或云集在某一处。强调成群结队地运动。引申可表示“充满”“挤满”等。
2.swarm只用作不及物动词,多与介词with或副词about连用。

swarm about(v.+adv.)
成群四处游荡 go everywhere in a crowd
▲swarm about
Bees swarmed about in the orchard.蜜蜂成群地在果园里飞来飞去。

swarm across(v.+prep.)
蜂拥着穿过 pass in a crowd
▲swarm across sth
They swarmed across the bridge.他们蜂拥着穿过那座桥。

swarm back into(v.+adv.+prep.)
成群拥回 return in a crowd
▲swarm back into sth
When the rain started the crowd swarmed back into the hotel.雨一开始下,人群就拥回旅社。

swarm out of(v.+adv.+prep.)
蜂拥而出 go out in a crowd
▲swarm out of sth
When the bell rang, the children swarmed out of the school.铃声一响,孩子蜂拥而出离开了学校。

swarm with(v.+prep.)
挤满; 充满 be crowded with sth/sb
▲swarm with sb/sth
The stables swarmed with flies.马厩里尽是苍蝇。
The swamp swarms with mosquitoes and other insects.沼泽地里到处是蚊子和其他虫子。
The open tents swarmed with mosquitoes.蚊子在敞开的帐篷里成群地飞来飞去。
The house swarmed with rats.这屋中老鼠群集。
The beach is swarming with bathers.海滩满是浴客。
The scenic spot swarmed with tourists.这个风景区挤满了游客。
The White House rose garden was swarming with security men.白宫玫瑰园里密布着保安人员。
I swarmed with the work at the present.我目前被这个工作弄得苦不堪言。

用作不及物动词
▲S+～(+A)
When bees swarm, hundreds of them come together in a great mass.蜜蜂搬家时都挤成一大团。
Customers swarmed before the counter.柜台前挤满了顾客。

swarm还可用作名词,意思是“蜂群, 一大群”。