verb
1.
to spread or swarm over in a troublesome manner
lawns infested with weeds
Synonyms: beset, overrun, overspread, overswarm
Related Word: abound, crawl, swarm, teem; annoy, harass, harry, pester, plague, worry
2.
to live in or on as a parasite
a dog infested by fleas
Synonyms: parasite, parasitize